[eurekin]

I can answer from my experience.

I've learned about mac text editors from online ruby on rails tutorials. Both TextMate and SublimeText put me in awe, coming from windows based development they seemed much more polished. It was specifically marketed as distraction free and a lot of my university peers preferred them over whatever tutors were trying to push down our throats (mostly eclipse at that time).

I'd hazard a guess it's just marketing that makes the difference in popularity. I've seen both Sublime and TextMate being used a lot in talks. They tend to present very well in, ehrm, presentations. Try doing that with UltraEdit. Toolbars and other "cruft" get in the way