It may be the "hard way", but as a PDP-8 user, I applaud it. Emulating
the drive rather than the bus interface means that one drive will work with
more than one machine type (and that tends to be Q-Bus-only because of
what's out there and in what quantity). Also, you should be able to put
this on the same drive chain with "real" drives.
Of course there is a place for bus-level device emulation (since not
everyone has an RLV11, an RL11, and an RL8A), but they are out there and
it's good to have something to attach to.