Bad games exist. Good games exist. I'm amazed at how many people try to sidestep these facts.
Sure, there's a lot of personal preference. Some people liked the die-roll system for actions in Morrowind (tell the character to swing a sword or pick a lock and the game will tell you if it happens) and others prefer Oblivion's personal involvement, modified by skill. Either can be a good game if it's designed right (in Oblivion's case, the minigames were designed horribly because character skill had almost no bearing on your success. But it CAN be done well and be very immersive).
But look me in the face and tell me that anyone will be happy if TESV continues the trend of less dialogue, fewer books, fewer factions, fewer quests, fewer skills, flat level scaling, identically-equipped dungeons, generic environments, and inferior lore.
What trend? Of course introducing voiced dialogue results in less of it, but they can only improve in amount from there. As for fewer books, are we including Arena, which had no books? Oblivion may have introduced less books than Daggerfall and Morrowind, but where is the proof? Find me a total count and I'll believe that claim. As for fewer factions, notice that in Daggerfall, none are fleshed out, all knight factions act the same and all templar factions act the same, effectively resulting in only 6 joinable factions in Daggerfall(Thieves' Guild, Mages' Guild, Fighters' Guild, Dark Brotherhood, knightly faction, and a templar faction; whether it's military or not, it doesn't matter) that aren't fleshed out at all while Oblivion, with KotN and SI, has 7 fleshed-out joinable factions(Arena, Thieves' Guild, Mages' Guild, Fighters' Guild, Dark Brotherhood, Knight of the Nine, Court of Madness) with several other not fleshed out ones(Blades, Knights of the White Stallion, Knight os the Thorn, Nine Divines). As for fewer quests, again, I point to Daggerfall's randomly-generate quests that come from a very small variety of boring formulas obviously designed for cutting and pasting. Oblivion's quests are the most original of all quests in all TES games, and are more numerous in number than both Arena and Daggerfall's quests, considering ones from the same basic formulas unsurprisingly are just as uninteresting and repetetive as all others sharing their basic formula and even those that don't share their basic formula).
As for fewer skills, again it's ahead of Arena's 0 number of skills, and, while I dislike a fewer number of skills, shaving off some of the more useless skills of Daggerfall in the transition from Daggerfall to Morrowind then to Morrowind from Oblivion was for a reason. I don't really agree with it completely, but it's not a trend that is there just to get the series closer to being casual heaven. It has reasons behind it. As for level-scaling, I can't say much about it, but what trend is that a part of? People complained about Morrowind being too easy, and level-scaling gets kicked up ONCE from the level-scaling of its predecessors. I can't agree with artifacts and unique items being permanently stuck at one level, though. As for identically-equipped dungeons, again, I refer to Arena and Daggerfall. Their dungeons were all boring labyrinths with no sense behind them other than making them unnessarily long, boring labyrinths. Oblivion actually did have dungeons that were unique with some interesting stuff in them(Vilverin, Fort Urasek, Sideways Cave, Black Rock Caverns), and I'm only referring to ones that aren't quest-related right now. Those aren't even all of them and those don't include any from SI. What's so unique about Morrowind's dungeons? I've explored a decent number of them that seem to be there just to be there.
As for generic environments, again, I point to Arena and Daggerfall, which were far more generic than Oblivion was, and again, that is without SI. As for lore, why is that so? That is a matter of taste, is it not? From Oblivion, knowledge of the Ayleid language was learned as well as knowledge of their culture, social structure, role in the history of the empire, and even how they disappeared. The first and last pieces of knowledge learned are lacking from knowledge of the Dwemer. Oblivion also contained much other information about the history of the empire, including knowledge of Morihaus, Alessia, Pelinal Whitestrake(thank you, KotN), the Chim-el Adabal, and much other knowledge, With SI, much about Daedric Princes(specifically Sheogorath and Jyggalag) was known and, even without SI, knowledge of a Daedric hierachal structure was learned. Whether you find any of the interesting or not is YOUR opinion, but claiming it is inferior to whatever you are comparing it to(I know you couldn't have played Arena or Daggerfall due to some of your claims, so I'll assume it's Morrowind)as a fact is just as you claim Oblivion is broken as if it is a fact. It is just your opinion, not a fact, unless you assume that me finding it just as interesting as Morrowind's lore means that there is something wrong with me and that I must not be realizing the absolute truth. If that is the case, then I'm proud to claim there is something wrong with me.
I love all four numbered Elder Scrolls games(haven't played the spin-offs, yet, so I can't comment on those), but some claims are just ridiculous and, in the case of your claims, seem to ignore the first two Elder Scrolls games(Arena can't come close to Oblivion and those who claim Daggerfall is much better due to more of everything usually fail to mention the boring generic-ness, true generic-ness, of it, and the same is true for those comments claiming all of Tamriel is explorable in Arena).