Hey,
People like the Triton because it is a one-stop solution for making tunes. It has an integrated sequencer, multitrack recorder, sampler, PCM synth, plus a weighted or semi-weighted keyboard which is good for performers. You can burn cd's with it, import different sample formats (Akai, EMU, WAV, etc.) from sample cd's, master your tracks, and pretend that you are a big time producer.
You can also expand it with different options, from digital i/o cards to PCM cards to the exciting MOSS card, which gives it the possibility to become a 'proper' synthesizer.
The one thing which sets it apart from the rest is its touch-screen which gives the user much easier access to the OS and all the synth's functions. I've played with one in the shops, it's very cool to be able to simply point and drag things on a little screen instead of messing around with buttons and knobs to navigate. However, I couldn't imagine what a nightmare it would be if this thing ever went bad, it probably costs a small fortune to replace!
However, in the studio, producers aren't using it for its sequencer(they use a software sequencer) sampler (they use their own Akai/EMU samplers), multi-track recorder (they're using Pro Tools or something computer based)...they use it because the sounds on it are fresh and because it looks GOOD to have a silver keyboard in their sonic arsenal.
While there are lots of studios and producers who have the Triton, there are even more who do NOT haver the Triton. And I'll bet my copy of Cubase that most owners don't even learn how to do anything else with it except play a few of the preset sounds and tell people how they 'gots a Triton, yo...'.
Nick