Honestly, what I think of most from Morrowind-->Oblivion is that point in Morrowind where you do (as I recall it) a loop of enchanting stuff that increases your potion-making, potion-making for better enchanting ability, etc., until you get to this sudden point where you can make insanely-powerful uber-enchanted stuff.
Now frankly, sounds dumb, and terribly stupid, and pointless. Sounds kind of game-breaking, really.
The thing was, it wasn't un-fun at all. It was the most entertainment you could have in a game at the time.
Definitely. I actually played Morrowind long after first playing oblivion and I have fonder opinions of Morrowind, which is weird personally since I'm no retro game fetishist.
It seems like the enchanting is game breaking, and in some senses it is (like the first time you craft an amulet that increases your mercantile skill by 300%, and can now buy items from vendors then immediately sell them back for multiple times the original price) but by the DLC on the hardest difficulties the enemies start catching up; there's even that one beggar dude where it appears there's no way to beat him without unnaturally juiced up enchants/potions.
To this day I'm still not sure if encouraging players to break the game was a deliberate design choice.
Oblivion has spell creation which allows for some interesting stuff (especially via stacking spell debuffs), but it isn't anywhere near as unhinged as Morrowind.
Skyrim's spells are terrible, but it has a similar looping structure to Morrowind where enchanting and alchemy feed into each other, then into blacksmithing, where by the end you're killing dragons with like 3 hits on legendary and your paralysis poisons last for 3 minutes at a time.
They've all got their quirks, but Oblivion's quirks are the least engaging imo.
Speaking of difficulty, fun oblivion fact: the difficulty slider for the game only applies a static debuff to your direct damage, and a buff to enemies direct damage to you. However it
does not modify either summons (the damage they do or take) or poison damage.
That means if you just use summons and poisons, the game will be exactly the same difficulty no matter what you set the difficulty slider at. That's one of the reasons it feels so bizarre, and why summons are probably the most useful of any of the recent games. Thanks Oblivion.
The game's got redeeming traits and going through oblivion gates is pretty cool, but it's just so dumb in so many other ways. I'd rather either play Skyrim or Morrowind.