Because we can. I didn't buy SWTOR because it was a MMO but because it was a RPG. I bought it despite it being a MMO. I not even a Star Wars fan as far as the movies go. Still I liked K1 and K2. That is why I bought it. As already been pointed out the options are there to play the way you want to. So what does it matter how someone else plays.
As far as money spend for solo's well their money is as good as anyone else's. So why shouldn't they get content.
This is a general statement. You can contact my reps Larry, Darryl, and Darryl if you disagree. They are residing south of Nashkel. You might even get a electronic autograph..)