Yeah I m agree, but not possible every time, for dreamcast CDI and GDI are not the same thing but it s the same emulator. I have an amstrad emulator wich run disk (.DSK) and cartridge (.CPR) and some amstrad emulator don't support zip format (from my memory).
My amiga emulator run ADF, but there is a possibility for big game to use direclty the whdload format.
obviously, It s not a priority because we can rename/zip or use 2 systems (1 for gdi and 1 for cdi), there are others priorities where we can do nothing, but I think It will be something usefull in the future.