You (and the OP) fail to mention the main advantage that sheet music has had over these alternate forms (I know that in celtic music they have tab, which is like this but for mandolins, banjos, etc), and one of the reasons that it has survived this long despite being pain to use: portability.
It is extremely easy to port sheet music from one instrument to another, in most cases this doesn't require any change in written music itself (Or at least, if it does the change is usually very trivial). Conversely, this new format is limited to the piano. I doubt that it would be trivial to port this music to the violin, for example (assuming the violin has a similarily structured music format).
It is extremely easy to port sheet music from one instrument to another, in most cases this doesn't require any change in written music itself (Or at least, if it does the change is usually very trivial). Conversely, this new format is limited to the piano. I doubt that it would be trivial to port this music to the violin, for example (assuming the violin has a similarily structured music format).