I wouldn't say literally all of his objections apply to Oblivion, and I think largely what impacts his perception is the overall summation of problems present in both. I'll break it down into my main gripes with Skyrim, things I think it did better, and a brief summary of what I think could correct the problems.
Cons:
Personally, for me the dialogue issues were some of the biggest problems. I didn't feel like I could really talk to anyone in many of the towns I went to, or if I could, the dialogue options would be utterly dismal. People say the same thing is true of Oblivion but I completely disagree, at least as far as the average NPC is concerned. I only remember encountering a few NPCs in the game that had very little dialogue or no unique dialogue options. I've seen people here advocate for even less dialogue options/interactibility and way more NPCs but I don't personally feel this would benefit the series at all. I've also seen people mention that it's unrealistic to be able to interact with every NPC in a given area but I feel like this isn't the case and that it would largely impact player freedom. I'm not going to argue that Oblivion had way more interesting NPCs than Skyrim, since I don't think that would be beyond a stretch to argue, but I just feel like on average, the towns/cities felt more... lived in.
Other than that, during my time playing Skyrim, I encountered several quest-breaking bugs and generally jarring quest sequences (Cidna Mine, some stuff in the Civil War questline, etc.). One could say that Oblivion was glitchy as well, but never do I remember even once in my 1,000+ hours spent playing Oblivion having a quest broken due to a glitch. One could also argue that both games were equally crashy, but personally, Oblivion would crash about every 1 - 3 play sessions, whereas Skyrim seemed to crash about once every 4 - 5 hours.
In regards to your comment about your frustration of a total non-mage being able to become the arch mage in a matter of hours, I mostly agree with you. I do think it should be possible to join a guild even if you are mostly a warrior but I think after awhile there should be systems in place that hugely impact your ranking in the guild and how far you are able to go in it. I feel like even though the same thing could be said in both Oblivion in Skyrim, the leap from newly-joined mages guild associate to arch mage is more prominent in Skyrim due to the fact that the college questline is much shorter than the mage's guild questline in Oblivion (I personally disagree with some that it's a totally bad questline and I enjoyed many parts of it, although I think that the necromancers were too unidimensional). Ultimately, it's the sum of the parts, rather than specific things that both games share, that seems to be influencing his (and to an extent my own) perception regarding Skyrim. Related to the magic guild, something else I disliked in Skyrim was how shallow magic actually was. I really loved how it felt and I'll definitely had the best magic feeling/look in any TES game, but I think the spell effect variety needed to be much deeper by about 4 or 5x what it is (I don't mean this just in regards to 5 fire damage vs. 10 fire damage, but different effects entirely). I also hated how there were barely any unique spells to find in dungeons. A warrior can find a rare blade or axe, why can't a mage find a unique spell (although Oblivion definitely didn't do this either)?
I also wholely agree with you in regards to your comment about attributes being cut (not sure how this one would relate to Oblivion, other than the system itself being too clunky/redundant in the game). There was a lot that could have been done with them and there still is a ton of use for them. Ultimately, I agree that it led to every character sort of ending up the same, although I think that was largely a problem with many of the shallow perks as well. I thought some of the perks were great but some of them wouldn't allow you to see any difference in character performance.
Further, I also didn't like the quest writing and I can only remember at most 5 quests that I ever experienced during Skyrim (I even remember Cidna Mine but not for how good it was). I felt like quest-wise, a step back was taken from Oblivion. I also didn't like how many of the quests would seem to advertise factions (although similar things happened in Oblivion, just not to the same extent, I would argue) and ultimately feel sort of like the game encouraged the player to do everything all at once.
Pros:
Unfortunately, my list of pros probably won't be as long as my list of cons, but that's just due to my personal preferences in regards to what Skyrim presented.
I really liked the world design in Skyrim much better than the world design in Oblivion, although I did find some parts of Skyrim to be a bit repetitive (The Rift and The Reach in particular). Still, I ultimately enjoyed the different mountain trails, drastically different areas of scenary, etc. more than I did in Oblivion (although I will admit that Cyrodiil had a certain charm, but that might be due to Oblivion being my first TES game more than anything). I also feel like Skyrim had the best arcane feel to it and visually portrayed just how weird the series can be better than anything previously (in terms of visual/graphical effects, not story-wise or anything relating to world-portrayal so much). The magic system also felt better than it has ever felt before, and I definitely loved the inclusion of perks into the TES series. I also liked the armor and weapons in Skyrim much better than Oblivion (with the exception of a few daedric artifacts in Oblivion and Dawn/Duskfang, which is still probably my favorite sword in TES). Smithing and crafting were also welcome additions into the series, along with numerous other small touches like this (jobs, food creation, etc.).
Ultimately, I certainly like Skyrim and admire many of the systems that it put into place but I don't really feel like it went as far as it needed to with fleshing almost any of them out. I'd say it improved in many ways from Oblivion but I think that most of those ways were more so action-oriented components and things that relate to general aesthetic and world flavor. Still, I felt like it had a bit less soul than Oblivion had, but I don't really expect many people to agree with me here, as this perception comes from my own unique preferences.
Future directions:
Personally, I think what they should have done/could do is input attributes and had them mediate perk efficiency. Did you just get a perk that allows you to run faster? Well, if you have an Agility/Dexterity of 5, that increased running rate isn't going to help much, but if you have an Agility/Dexterity of 50, then you'll see a major increase in the perk effect. Did you just pick a perk that allows you to knock people down with certain blows? Well, if you have a Strength of 5, that probably won't help you much, but if you have a Strength of 50, then you'll be knocking people all over the place with your heavy blows. So on, so forth from here. I also think that attributes should also have independent effects as well, i.e. intelligence leading to you filling in journal entries better, endurance meaning that diseases impact you less harshly, although I could also appreciate a system that would have these things join in as perks as well.
In regards to factions, I'd prefer to have a layered system for each faction. There could be training-oriented components to a faction, job-oriented components to a faction, and story-oriented components to a faction. I'll just use a mage faction as an example since it's easier for me to think of. When you join a mage guild, you start off as an associate, something that anyone can achieve no matter their aptitude. Moving up in the guild, however, would involve receiving letters of recommendation from higher ups by participating in "learning activities," such as going to some in-game "lecture" about lore behind certain magical classifications/spell types, magical history of certain buildings/areas, etc., in addition to practicing new spells with fellow "classmates" or things along those lines. One could also complete jobs that are appropriate for their rank, which can also help them increase their overall rank and not all of the jobs would necessarily require magical use. Ultimately, there would be a limit to how far a non-mage would be able to go, though, without completing certain "learning" activities and mastering certain spells/techniques, etc. Lastly, there would be the story layer of each faction, which could slowly unfold once the player reaches a certain rank/standing in the guild.
But yeah, I feel like this is starting to get into a bit of beyond skyrim territory, so I'll leave it at this for now.