(dunno why I didn't use 'Morrowind' as a tag, lol, oh well)
I read here how everyone is still enjoying the bananas out of Skyrim, and perhaps Oblivion, too.
However, for me, Skyrim (and Oblivion as well) lacked a great deal of something - immersion.
I played Morrowind for over 5 years (not playing much else), and still only felt like I was maybe 30% finished with the game. Every time I played it, I felt as though I could walk in one direction for 5 minutes and find something completely new! In Skyrim and Oblivion there was zero mystery to me! Morrowind - "Hey, what's that tower in the distance over there?!?!" Skyrim - "Ope, another fort, cave, redoubt, etc, etc (ugh)".
I can't tell you how many hours I logged trying to just find cool stuff in Morrowind. In Skyrim and Oblivion, there's no secret treasure, hardly any secret pathways, and it seems as though every quest is dumbed down to "go here, get this, bring it back". I'm aware that Morrowind had plenty of those, but Morrowind felt that it had depth, a story, a real reason why you went out to each location - not to mention the uniqueness Morrowind boasted... "Can you escort me to Hla Oad? *gives you Boots of Blinding Speed as reward." The most entertaining fetch quest (I hate calling them that) was needing to find a Daedric Dai-katana in a shipwreck east of... Tel Mora was it? Just finding the bloody shipwreck was a challenge! - and good, I was glad! (I think I've used enough italics for one post).
Another big difference between the 2 games, was the stat tracking. Instead of a grand enemy, impending conclusion, great end to a questline, all I felt Skyrim gave us was a numeric ticker for questlines. "Questlines completed - x/xx". I think many remember the final boss in Skyrim - what a letdown.
However, Skyrim is still a beautiful game, in many ways. Jeremy Soul should be swimming in cash at how beautiful his contribution was to Skyrim - I listen to the 3.5 hour long soundtrack at least once a week in the car (I drive a lot for work). It's so beautiful. The landscape, gorgeous, almost as unique as Morrowind (despite how "bare" Morrowind was given the Xbox's limitations, it still takes the cake). The armour sets were all very unique - Glass Armour and Weapons are the best looking, in my opinion. I was disappointed with Daedric, but oh well.
Bottom line, to really make my point, I felt like I difinitively knew when I'd be done with Skyrim. All the locations found and marked "Cleared", all the Questline tickers accounted for, all of the houses owned, etc, etc, etc - they may as well give us a 100% completion status like GTA! (although I like it in GTA - totally different there). In contrast, again, to reiterate, I could play Morrowind for another few years and not quite feel finished!
To conclude, although Skyrim has many things going for it, I would love seeing the next ES be as immersive as Morrowind was. Can you imagine? - graphics/controls/environment interaction better than Skyrim, but with Morrowind's immersion.