Why should being based on improvisation and unique personal expression be the be-all-and-end-all of analysis? Not everybody wants to play / hear improvised music.
Classical music is dying, because the audience is literally dying of old age. Jazz or folk can sustain itself as a niche pursuit, because a small ensemble can profitably play to a small audience; a symphony orchestra has an enormous wage bill and has to fill a large hall week in and week out.
Classical music can renew itself and guarantee a sustained future, but it can't do it without fundamental structural reform. If classical musicians want a secure future for their art form, they need to seriously reflect on what classical music is, what it could be and what it needs to be. It's not enough to offer cheap tickets to under-30s, it's not enough to have the odd pops concert in the park - lip service will not abate an existential threat.
https://www.artsjournal.com/sandow/2011/03/age_of_the_audien...
Jazz is more amicable to diversity than classical music on a fundamental level, because it's based on improvisation and unique personal expression. If you're physically unable to play the same way as everyone else, you're pretty much useless to a classical orchestra but you may well become a pioneer in jazz.
Some obstacles to diversity can't be overcome with blind auditions and quotas and sensitivity training. Some environments are lacking in diversity because they are structurally incompatible with diversity; they can't have diversity retrofitted on to them, but need to be reformed from the ground up.