The thing about KoTOR, and most standard CRPGs, is that the focus of the plot is the main character, played by a single person. When you involve more people, and they have very little to do with the plot and basically serve as combat support, it tends to get boring.
Unfortunately, a good plot line like KoTOR would not make a good MMORPG, because of that. After all, how many Chosen Ones can one Galaxy have?