On the subject of Morrowind vs. Oblivion, there is a lengthy list of failings of the latter relative to the former:
I agree with a lot of these. I would note that I've already agreed the world of Oblivion is very boring and that Morrowind's is self-evidently better, which covers many of these points. To pick out some that I don't agree with though:
Reduction in the number of joinable guilds/factions offering many quests from 10 in Morrowind to 4 in Oblivion, keeping the more generic ones (Fighters/Mages/Thieves guilds)
This is obviously true, but a lot of the factions in Morrowind offered incredibly boring cookie-cutter fetch/kill quests. Oblivion has less joinable factions, but the ones that remain offer far more interesting* content than Morrowind (with all the usual disclaimers about how everything in Oblivion is in some way shit).
*interesting in terms of quest premise and structure, not necessarily in terms of worldbuilding or loredump-iness
Full voice-acting for dialogue, which necessitated a drastic reduction in the amount of dialogue per NPC, most of whom have one comment about themselves or their city to offer and nothing else
In Morrowind, many NPCs have no unique dialogue at all, and many others have one or two unique lines just like in Oblivion, the rest being generic wiki dialogue. There's no real difference between some generic Oblivion NPC who says "Hello, I'm Dickius Headius, and I work at the Bandit Camp. Let me mark it on your map" and, say, Eldafire from Seyda Neen, who as far as I know has no unique dialogue except "go clear out the smugglers" (which I think is her "Little Advice" or "Little Secret" dialogue).
Automatic fast-travel to any location that's already been visited
This is a tough one - I think there's advantages and disadvantages to both systems. I've played Oblivion and Skyrim with mods that disable fast travel and to be honest it just renders the whole experience very tedious. I think they were ultimately right to allow for fast travel to all previously visited locations. Having to walk to and from Silt Strider ports or docks in Morrowind does definitely give the whole game a better sense of place and feeling of verisimilitude, and does a lot to make the player consider how they'll reach each destination, but it's essentially just LARPy busywork since there's no real travel resources the player can deplete or anything. And again, the complete non-reactivity and stillness of the world means that the experience of walking to fast travel networks gives that "empty MMO where I'm the only player" feeling after a short while.
Morrowind, as with Arena and Daggerfall before it, does not have action-based combat, but instead a combat system with mechanics dependent on the character's skill, including to-hit rolls. It wasn't until Oblivion that Bethesda Softworks made an effort to make combat more action-oriented.
I think there's an old interview about Todd specifically wanting action combat in Morrowind and coming in and fucking it all up at the last minute, hence the results. In Daggerfall the player skill/character skill disconnect feels far less egregious because your attack speed is tied completely to your actual Speed attribute and you can't
really cheese everything by bunnyhopping around (though you still can to some degree). Morrowind has the incredibly stupid quick attack/power attack system, presumably there to make it feel more action-y, but the result is that you're choosing between spamming many die rolls and making one big die roll.