Enjoyment is popular, atleast in the entertainment business. A lot of people find CS fun, so they play. Frankly, I think it's dull. I find INF fun, due to the added complexity. Some don't.
CS, in its own respect, is "good" in the sense that they created a game that can be, and is, enjoyed by many. They have done a "good" job in appealing to wide audience. The game, however distasteful this community may find it, is [for all its purposes] done well. It is a "good" game, by those standards.
Do I enjoy playing? No. Do I ever play? No. Will I start to play? No. But thousands of people do, and they love it. Simple as it may be, sometimes that's what people desire from their entertainment. Look at television.
That being said... I'd love to try a Fort game. I never got to play, but it sure does sound like a lot of fun to me. I really enjoy take-and-advance style gameplay (Battlefield, Onslaught, etc)