On iOS, I don't think the term MIDI is mentioned anywhere in app. Unless you recalled it from the app store description then the Import button seems quite mysterious; average users might mistake it for something to interpret and extract notes from MP3s or whatever.

I have this site bookmarked for fun: https://bitmidi.com/ If I showed this app to some friends, the first thing they'd go looking for would be some video game music which is a whole different set than classical. Considering that, it would be nice to have separate libraries or playlists for genre organization. Offer some pre-populated as IAP, e.g. Classical is default but you can get popular songs, SNES tracks, etc. for $1-2 per collection if doable with individual licenses.