The reason I'm not running it right now is lack of good binary packages and a good package management system. I don't have time to mess around with source builds which may or may not work. I want an upgrade path that has a good probability of working, and if it is going to fail I don't want to find out about it 20 hours later when I'm not around to figure out what went wrong.
I've never been a fan of linux, but my vote goes for apt/dpkg, which I've had reasonably good success with. Definitely moreso than ports + portupgrade (which has hosed my system far too many times). > Maybe those 90% you are talking about don't run DragonFly in the first place?