Both of these things do not happen in the NFL so making it so you cannot do them seems fine to me. To me it seems the forced drop back would elminate these things and I don't see it hindering or limiting the ability for the QB to move or make a quick throw.
None of us know how constraining the drop back will be and I don't think it will very constraining at all.
The forced dropback should only force the first two steps at most and will not make it impossible to throw a quick pass.