Expect an Elder Scrolls game. Don't expect exact details, just expect an Elder Scrolls game. Do you really only own those three games and Oblivion? Of all the games in existence, TES games, above most, if not all, others, are games to be bought. Oblivion, as an Elder Scrolls game, is no different. I've been playing it on my PS3 for the past year and a half and I'm still playing it. Three months is a long time to be borrowing a game. That's all I will say.
Well, I payed for Oblivion when it came out and was really disappointed. Because, honestly three months isn't long enough if I'm gonna pay for a game.
Learned my lesson and waited for my brother to beat Fallout 3 and he gave it to me for free. Since I didn't pay for it, I expected nothing, like you say. I actually expected it to be a straight-up action game, that's the amount of faith I had left in Bethesda at that point. I was very pleasantly surprised when I found a settlement in which I can trade and pick up side quests. Ended up enjoying the game immensely for months. Had I spent money on it, I would have been very angry and hated the game.
Same thing goes for Fable 2, paid six dollars for it, so glad I didn't pay full price. Never bought Two Worlds, Dragon Fable, or Mass Effect 2. Morrowind has spoiled me for RPG video games. I refuse to buy another RPG unless I know for a fact it'll keep me entertained for as long as Morrowind.
On another note, what keeps you playing Oblivion? Maybe I can get back into it if i look at it differently. Because I will admit I was going through the opening menu to see what nords look like, and I was a little enticed. I can tell you the things that really turned me off and made me sick of playing were A) the sheer lack of quests/spells/dialogue/weapons/skills and B ) "You cannot sleep in an owned bed).
Honestly those two things, especially the owned bed and lack of skills, really left a sour taste in my mouth and I noticed myself missing Morrowind, ratehr than enjoying Cyrodil.
And @ Kovacius: yes, streamlining is the enemy. They try to "balance" and "simplify" by trimming away the "unnecessary" skills and weapons and spells, but always end up shaving away a lot of the fun, as well.