It's simply matter how much you can customize your keyboard.Oriental players rarely use factory styles or voices.
On Korg they can make their own styles right on the keybord,and there is full blown sampler and synth engine.Korg support AKAI format for importing samples.Yamaha is good too but most of these things simply you can't do.Even on T4.T4 doesn't even take samples from T3/T2.You still have to convert them,and good luck making styles on the keyboard from scratch.You simply can't.Should it be there,I think it should especially on T4.But,it was made for home player and not for professional musician.