I think I get where they're coming from. String and wind instrumentalists generate their own LFO, which gives them more expressive control. My best guitar patches map aftertouch to a slight raise in pitch, so I can simulate an actual guitarist's vibrato.
That said, I would have liked MIDI, if for nothing else, to be able to use the keyboard to trigger other boards' sounds when I need a second manual but don't need its native engine.
BTW, reading the synth engine specs ('cuz I couldn't get a lot of audio):
2 Oscillators (sine wave, phase modulation, frequency randomization) 2 Shapers (sine curve, adjustable foldback and asymmetry)