I don't understand why everyone's trying to say focus on one class you really like, 'cause there's 9 classes to choose from... So why not be good at them all? I like to vary it up when I play.
I think it stems from people getting comfortable with a certain class and then, when they decide to switch to a different class, they find that they're terrible at it- nobody wants to feel like they're terrible at anything- so they stick to the class that they're good with. Also, some people (myself included) have, at some point, paid attention to the ranking system; and I can tell you it's hard to pull yourself away from that when learning a new class (your stats will undoubtedly hit the pooper). It just takes a lot of time and a lot of patience.
















, and Wilson for example are good to watch as far as seeing the limits of each class etc.