This indeed sounds amazing, not only for disabled people, but having better sound experience benefits everybody really.
I'm just concerned about what kind of stress on the game would be produced by every single thing having unique sound. And what kind of space on players disk drives would that consume (not gonna mention on how long development time would be extended by doing this).
I'd personally be interested in seeing this upgrade down the line, post release, if game shows successful enough to warrant the investment, and if tests show game wouldn't be tangibly more stressed by this.