To me they all sound rather crap, but as a professional musician I find keyboards like that to be simply lacking depth of a real thing. I would take just well recorded piano, over what is in this video. Games are big budget productions and they can afford better then that.
That said Piano itself is capable of a rich soundscape, especially if you dig into extended techniques, like here:
Still, it is highly impractical requiring a lot of figuring out, recording, "preparing" the piano and editing. The popularity of big ensembles is that you have a rich soundscape to choose from, and less dealing with individual instruments limitations.
I think "piano" solo OST would be interesting, but for a right project and right person behind playing&composing.
