It's a perfectly rational design, because what it is doing is performing in exactly the same manner it does in Normal Law. A pilot whose commercial experience consists entirely of FBW Airbus time is going to find it easier to have autotrim on when things go awry than to suddenly have to cope with manually trimming the aircraft.
Let's be honest, how hard is it to understand that one does not make large and sustained inputs - which is what these were, make no mistake about it - without a bloody good reason, even more so at altitude?