I'd like to buy my first keyboard instrument. I want a piano touch with 88 keys and MIDI output and otherwise extremely minimal features. I'm hoping this will allow me to experiment with different sounds over the lifetime of the keyboard rather than being locked in with the sounds that are normally built in to a digital piano. By moving the sound production out of the keyboard, I expect it would also be lighter and easier to transport (several smaller components instead of one large keyboard).
Is this a bad idea? Is MIDI limited in the sound quality it can produce in any way? (I.e. can I produce completely natural sounding music with it?)