Lack of developers... lack of time... those two things factored into the equation and it doesn't equal lots more mods. Many people would be intimidated by making mods for ubb. People are leaving, losing interest and time, etc. The good news is the features in UBB are increasing. The bad news is the hacks at ubbdev are decreasing.
I'm not one to really talk. I just left an official position a week or two ago after developing no new hacks and not supporting the ones I already made. I have a dozen uncompleted hacks for various versions that I can't (and don't want to) complete.
Just my $0.02.