i wish the mp3 thing weren't such a can o' worms but i'm still in favor of including it for both gameboy and a hypothetical LSDJ format. but this is not a thread about the gameboy mp3 worm can (mostly)
i think a point in favor of this format is that LSDJ has a specific, more diverse set of abilities than any other gameboy tool. if you listened to a bunch of gameboy mp3s without knowing in advance, the LSDJ ones would be obvious. the wave channel synths, double drumkit notes, tables, gnarly fast vibratos and retriggers, etc etc, all give LSDJ a unique take on the gameboy chip... and it's very widely used.
that said.. in my opinion nothing is stopping you from making an LSDJ-focused series in the gameboy format, and just strongly encouraging the use of LSDJ (or even requiring it?). this isn't really a point *against* the idea of the new format so much as i think you could do this already, regardless of whether this format happens!