Huge numbers of young people learn traditional music notation all the time, yes, but I wouldn't say with little stress. Music notation evolved much like English, and much like English it's widely recognized to be full of kludges and unnatural constructions. And similarly, changing it would resemble switching to Esperanto.
To add to your point, many people already use other systems. Tablatures are very, very common for guitar. Lead sheets are used in jazz, and they do away with many of the problems of regular notation (notably, the legibility of chords, and different clefs) by only using it for melodies. In a way, traditional music notation is really only used in classical music. And they're never ever going to adopt another system. The people who wanted another system have already split off.
> traditional music notation is really only used in classical music
And jazz and pop and rock and.... It is a universal language that allows musicians from many backgrounds to come together and play a tune together. Jazz is the most obvious example--where musicians often sightread a tune together. (Although, to be fair, a substantial part of jazz notation is chord symbols, which are not (directly) a part of traditional notation.)
tabulature is really just used for starting out on guitar in my experience and it works because the alternative is SO approachable and SO instrument specific.
lead sheets are solving a whole different problem and almost ALWAYS have the melody in traditional notation in addition to the chords. some lead sheets assume you already know the melody and can transpose to whatever key is relevant.... but still a lead sheet is there to give you hooks in order to aide improvisation.
jazz musicians have not "split off", they have added some chord notation above the traditional stuff.
