Traditional sheet music is already like guitar tabs for piano, because pianos (unlike guitars) only have one physical place where you can play a given note (like middle C). The reason guitar tabs make some sense [0] for guitar music is that "middle C" on a guitar can be played on several different strings.

[0] I say "some sense," because tabs are still fairly limiting, particularly in depicting complex rhythms. Traditional sheet music is still very common (and, I contend, indispensable) for advanced guitar study.