Probably because "flagship" creators are too busy to do stuff like this, or just don't visit the forums :B
(.... I'm sorry I have a grudge against a few of the flagship creators, apologies u o u)
Honestly, we shouldn't need those characters though. This is more of a community thing and the people who have taken the time to personally stick their stuff in there are the best. That's what Tapastic should be about really - community and coming together to make something awesome, not having the most subscribers/supporters/etc. /but i digress like shit