The only great use-case I've seen for the pro is 2d digital art. I have a few artist friends who love the pro+pencil.
Music production on one really interests me, but none of my favorite plugins (effects and instruments) that work MacOS/Windows exist for the ipad. They also don't offer enough storage at the high end Komplete 14 Ultimate is 680GB. Each of the Spitfire sample libraries is near 200GB
There are some nice sequencing apps, but again don't need the pro for that, I just send the MIDI or OSC data to a "real" computer running a "real" DAW.