I read a couple of opinions which disliked drive letters.
When time goes by, we shuld think of a nice alternative
surely if we are aiming for 100% M$ NT compatibility, we have no choice but to go with what is already there. as far as programs are concerned, they should believe that they are running on an M$ os. loads of registry entries and .ini files refer to C:, D: etc.
I could imagine using UNC paths like "\mybox\mnt\cdrom\setup.exe" anywhere as replacement for drive letters. Perhaps one has to remain a single, small C: partition for programs, which don't understand to handle this. But you could get rid of mounting any of your otherpartitions at a drive letter.
However drive letters are not bad always. They can be used as shortcuts to deeper nested directories. By the way: XP also goes somewhat into this direction. You can mount partitions at any (NTFS) directory you like.
Regards,
Martin