keystring Everything is true what you wrote about LH and RH. And I am very aware of it. I was just simplifying it, because most of the time the LH plays the bass clef and the RH plays the treble clef.
And here comes another problem with 2 different clefs. Sometimes when the score has a lot of high notes, the lower staff is written in treble clef and the upper staff is a treble 15va. And suddenly piano players are forced to read the treble clef on the lower staff. Most piano player are not used to do it. This leads to confusion and often to wrong notes during learning. Not to mention how much more difficult this makes sight-reading.
Same happens if the music goes down and both clefs are bass clef (the lower with 15ba). And on top of that, when hands are crossed the RH must play a bass clef, the LH the treble.
It is not only to get rid of learning 1 clef instead of 2 different ones. Currently we are learning 2 clefs, but used in 4 configurations in total (treble/bass is probably used 90% of all sheet music, treble/treble is 5%, bass/bass is 4% and bass/treble is 1%). If you ask me, that is a heck more stuff to learn, compared to a single clef with octave shift indicators.