I didn't find Oblivion's story to be as bad as all that. You mention that you like JRPGs. I can't honestly say I've played all that many unique and compelling JRPG storylines once I played my first JRPG, aside from the Shin Megami Tensei series I should say. Most of the Final Fantasy series, for instance, deals with some evil that is somehow trying to exploit the earth, and you are a character who often doesn't care about that, until about halfway through the game when you realize that, "Oh shit, I live in this world too. I better do something about this." Both JRPGs and WRPGs seem to have their own feeling and setting that is emblematic to their storylines.
I find that WRPGs tend to give you more freedom to make up your own story, while JRPGs really want to tell a story, even if it is the same "you must save the world from the evil that is threatening the planet's essence. Oh and your travelling with a secret princess."
However, I do agree that the battle mechanics could have been smoother. But, when I think about first playing this game, I realized it was four years ago. I can only imagine that in Elder Scrolls V they will address this.
And the voice thing. My suspicion is that Bethesda just doesn't budget that much for their voice acting. With such a huge amount of voice acting in a game like Oblivion, they probably skimped just a bit too much. It was better in Fallout, which had a similar amount of voice acting so again I hope they'll fix this in Elder Scrolls V.
Despite it's flaws, looking back I would still highly recommend Oblivion to people. There are just too many positives to the game for it not to be included in a must play list for this generation of consoles.