Why? It's a Bioware-driven Star Wars MMO. That's three boxes ticked in the "money" category already. I don't like Bioware's games on the whole, but they're popular, and what you have in the making here is a way to cash in on three fanbases - and three different attractions to the game. I see this one running quite successfully, at least for a while.
I've no intention of playing it, but most KotOR fans I know intend to at least try it. Hell, I imagine most gamers with an interest in Star Wars are going to at least try it. We ran a poll on KotORFiles, and even in the heart of the Revan fanboy world, over half the respondents were stoked for the MMO. And that's arguably where you'd expect the most resistance to the idea.
I'm sure lots of people will try it, I just haven't seen anything that will keep them playing. I don't play MMO's though, so what do I know. But no one so far has been able to take on WoW.