Don't forget, pianos didn't even get to be 88's until the mid 1800's... Most of Beethoven's repertoire (except the very late pieces) can be played on a 76. ALL of Mozart can be played on a 76, and all but the most stretched out, whacked out jazz and pop piano music can be fit into a 76.

Not to mention, that extra octave makes putting THREE sounds on the keyboard less of an exercise in extremely limited range mitigation.... Finally! A full two octaves to play whatever inversion or voice leading change for the chord recognition, and STILL over four octaves to use for your RH...

Don't forget, the weight issue is simply a diversion. The E60 was a pretty full featured 76, at only four pounds more than an S910 (with a FAR better action). They CAN be made.