1) yes, Oblivion expects you to go be the hero. That's the story they wrote, and .. now this may be a silly concept, but last time I checked when video game developers make a game, they expect you to play the game and follow the story- they may have other options.. but if they didn't expect you to play through the story they wouldn't bother writing the thousands of lines of dialogue and code for it.
It does not FORCE YOU you go become the hero (well, the warrior who helps pave the way for the hero :p), but it's still the general expectation that the player will do so.
2) I'm disliking Oblivion because I played it, quite a lot, and the story never got my interest, and the world (without mods) was boring as fuck to roam and do things without following the story. The addition of about 20 mods (give or take) made Oblivion worth playing whilst ignoring the story. Oh, and I also disliked Oblivion because I only like level scaling in Diablo-esque games.
Skyrim, while it may railroad you in to the story more, offers a bit more options for those who wish to ignore the story.