you can have 999 midis on the sd card with 99 playlists, with each playlist having 99 songs, so just import the next batch of midis.

Yes, the KN8000 would have been much better but playlists are an incredibly easy way to organise midis since they use virtually zero space up on the card but give many possibilities of playback order, and far superior to a simple file list or folder organisation, since a folder list might be thought equivalent to a playlist, but many playlists can have many selections from different folders without having to duplicate midis in each folder which would be really significant wasted space on the card.

The existing structure was limited by having to cater for backwards compatibility with previous generations of floppy disks and 8 (realistically 6) character names while providing an internal system for longer more useful names. And naturally the KN8000 would have had to be compatible with 7k sd cards