you can't find the uber-weapon that gives you one-hit kills from here on, and makes combat boring. It's hard to imagine how they could give you a "wow" reward without creating some kind of imbalance
That's true. But I don't see that as a good thing. Do we want a game that babysits us, that prevents us, like an over-protective parent, from doing something that might cause some kind of problem? Or do we want to be allowed to game like advlts, to exert a bit of self-control?
Roleplaying is the art of creative self-limitation. As far as I'm concerned, "game balance" is only a concern for those who power game.
I loved knowing that there were unique, hand-placed items scattered across the game world in Morrowind. I didn't care if I never collected any of the stuff, I just loved knowing it was
there. There's nothing to be found in Oblivion that isn't dictated by my character's level. There's no surprise, it's stultifying. It's the item equivalent of the enemy level scaling that everybody professes to hate so much.
I like place-centric enemies and I like place-centric items. I do not like player-centric leveling and I do not like player-centric items.