Disclaimer: I make this argument from the dubious position of never actually having played either Morrowind or Oblivion. Yet. (...Please don't yell at me? I'll get around to it.) However, I have read a great deal about both games, so I feel like I have a pretty good handle on why the fandom at large, with a few exceptions, seems to worship Morrowind and despise Oblivion. I've also played Skyrim quite extensively.
Now, I'll admit that from what I've read, the mechanics of Morrowind (the magic mechanics, not the derpy melee) do sound pretty appealing. And Oblivion seems to have simplified it somewhat. Although afaict Skyrim simplified it far more, which is why I don't get the common view that Skyrim is the superior game and is only slightly inferior to MW.
But there's one simple thing that gives me pause about MW, other than the fact that this sort of fan consensus on the quality of a work is incorrect with staggering frequency.
It's brown. It's freaking brown, and everything being brown makes it an ugly game. And Skyrim had the same problem, although to a lesser extent -- it does have forested areas; they're just tiny and still kind of bleak. Oblivion seems to be the only current-era TES game that actually understands the concept of colors. Look, I don't care how "original" your scenery is. If it's all one color -- particularly if that color is a hideous one -- it doesn't matter. Also. Since when is a dust-covered wasteland original? Seriously, you can't go two steps without bumping into a game set in a desert where you can't see anything. Granted, I don't think the MMS glut had hit yet when Morrowind came out, but it applies today. A desert full of fungi is still a desert.
Actually, now that I think about it, wouldn't a mushroom forest usually imply tons of bright colors? Sure, mushrooms are often pretty drab in real life, but the fictional convention is typically to have them all technicolor. I mean, just look at Felucia. ...or, you know, Blackreach, actually.
Now, if Morrowind is somehow far, far more aesthetically pleasing than every single one of the screenshots I've seen would imply, please let me know. Otherwise...it just bothers me that everyone loves a game with such atrocious visual design. And hates the pretty one, and likes the one that's ugly but not quite MW-ugly. Seriously, that's the only attribute I can think of in which Skyrim is closer to Morrowind than Oblivion is, which raises the possibility that TES fans somehow value ugliness. And that disturbs me.
I do apologize if this comes across as overly aggressive. It's just that overwhelming agreement on things that don't make any sense...confuses and angers me.