isnt the fact that the sports sean mentioned are about using a ball. thats just because its a very versatile object, can be thrown, kicked, passed etc, and many sports have been created around it. the thing that makes these so popular, is the fact that they are introduced at schools. everybody goes to school(or should dfo) and at some point in their early life, will have played a sport. this is what introduces the sports to us, making them more popular.
the only reason paintball isnt as popular, is due to less chance of ppl being introduced to the sport, whether this is due to money, travel, time or actually knowing about the thing, is down to them, but slowly we are getting there, i found out my neighbour went yesterday and really enjoyed it, wants to go again.