Just a simple poll asking do you play any type of MMO? I know opinions vary on the site depending who you ask. I'm interested to see the results.
No, I'm in no mood to interact with other people after a working day full of socialising (talking to my wife is about the most I can manage). Also other real world people in my game tends to break the suspension of disbelief I have when playing. I suppose I could solo but it would feel like I'm going against the whole point of an online game.
IMO, there's no reason not to solo. Something like SW:ToR is perfect for at least 1 play through because it's built around a story. I absolutely avoid playing with people like the plague until level cap. With the exception of Raid/Dungeon content and PvP, it's far easier, not to mention faster, to play alone. Playing with a group of people you know & like does enhance the experience, but it's far from required.