You could .. avoid paying the manufacturer's fees for re-enabling features that the firmware has disabled? You could refill your ink cartridges?
Bad actors at this layer seem to be quite rare. And the whole reason everyone uses the unlicensed bands is the freedom to transmit (and expectation of recieving) arbitrary signals.
I think our experience is rather limited for the moment to tell (ok, barring refilled cartridges ;-), since bad acting is inhibited by existing mechanisms. (Even with cartridges -- what if your new yellow ink breaks that hidden watermarking that certain people have come to rely on?)
Compliant device receives an accepted designator (certificate), non-compliant device is not expected to have it. This model can easily be broken, unless it is being taken care of somehow in the new model.
Unlicensed bands are a tiny part of the entire aired RF spectrum -- and we didn't even start speaking of devices sharing a wired RF medium.