Bioware is now infamous for stating that Star Wars: The Old Republic would be the first MMORPG to incorporate the "fourth pillar" of gaming - story. This resulted in a flurry of blog posts espousing the various ways MMOs have already done story, and that SW:TOR won't be doing anything new after all. Honestly, if all Bioware is doing are novel quality quest chains with voiceovers, the critics will be right. I don't think story is the "fourth pillar". I think it's choice.
Currently in just about every MMO I can think of, when it comes to doing quests your choice is purely binary. You can choose to do the quest, or not. That's it. How you carry out that quest is out of your hands, you don't make any choices other than clicking "accept". A prime example occured to Tipa of West Karana recently. While playing Rift she accepted a quest that at one point required her to torture a member of the opposing faction. She found this repugnant, but as a player she had no real choices -- she could either complete the quest as instructed or abandon the quest entirely. There was no option to try and resolve the quest without torture.
A true innovation in the genre would be to allow a player to reach that point in the quest where they have to torture the enemy, and then say "no, this is not me, I won't do this, I can find another way", and then give them a path by which they can succeed.
So what I really hope SW:TOR will bring the to table, and that other MMOs will adopt, is to give the player choices in how they complete story objectives, much as Bioware does in their single player games. If those choices also have long term consequences, great! But at the very least give us meaningful choices to make as we progress our characters through the game.