connecting the piano with a keybord?

I assume you are speaking about a MIDI piano keyboard. Technically, it should be possible. However, it would require an entire new section of code to read incoming MIDI codes and route them to whatever code is currently playing the piano sound. I can imagine this may look to many a bit out of scope and perhaps a way to divert development resources much needed elsewhere. I also imagine that additional features, almost standard in a play package (ambient parameters, patch change, and so on) would look even more inappropriate an overload for an already very busy dev team.

Just my 0.02 €, though.