J.S. Bach's music is appreciated by all keyboardists, and not always because of its beauty or genius. His work is very cerebral, and obviously engineered to require intense concentration. The intertwining themes, voices, and melodies wreak havoc on your stream of thought; two, three, and sometimes four voices may be trading off between both hands, usually for multiple page-lengths. It is some of the best training any pianist, organist, or any other keyboardist can have, and all of the best composers (see: Beethoven, Mozart, Chopin, Rachmaninov) have been influenced by him.

It should be noted that all (not just some, not the majority, but all) the greatest virtuoso pianists have absorbed as much Bach as they possibly could. Any experienced musician will recommend that students and aspiring keyboardists have a daily Bach session whether they particularly like his music or not. The resulting improvements in technique and interpretation are more than worth it. Not to mention the show-off rights: nothing shows superior intellect like being able to play a three- or four-part Fugue.