Their style is well suited for animation, it's cartoony but in a way that it's conductive for quick, high energy movement. The fact that guys like Imaishi are westaboos so that gives their stuff more appeal outside of the usual audiences.
I haven't kept up with Trigger after KLK though that Rikka girl is pretty hot and I've been meaning to actually watch LWA one of these days
, and I haven't watched seasonal anime in ages. It's mostly been manga for me.