I think the tool would be far more useful if it did have these
   well-known commands built in; even if it weren't for the
   possibility of catastrophic typos, I'd personally much rather type
   "FORMAT" than "4 0 0 0 0 0" (it's shorter, if nothing else).

I don't even care so much about the additional bytes.  It's just that
if I tell a user to type:

scsi -f /dev/mumble -c '3 0 0 0 0 0'

then I have to be very concerned about that user suddenly having no
data on his/her disk.  If instead it was:

scsi -f /dev/mumble -c 'request_sense 0 0 0 0 0'

(or something like that), I wouldn't have to be concered.  It's pretty
damned hard to mistype `request_sense' as `format_unit' or `write'.

If the user is intending to do something destructive (like a FORMAT
UNIT), then it's reasonable to expect him/her to be more careful;
though an easier to use interface is obviously preferrable.