The whole point of couching is that it's not blockable.
Besides it's so easy to dodge if you see it coming (eg have enough time to block it).
Turn down the music volume and turn up the sound volume, you can hear horses with plenty of time to avoid being couched.
Compensation of some sort may be needed if you ask me
+1
They would need a big buff somewhere if couching became blockable.. And tbh I would rather be couched then improve something like the 1 hand bump&slash