I can certainly see how stunning could be frustrating, but there still might a way of making the 'excessive amount of physics displacement' a more consistent interaction - it already happens to some extent, you just don't really have much control of it as the designer, right?
Yeah, more environment interactions would be cool - the blob hitting switches closing doors, putting lights out and so forth. What was the goal with the NPCs? What sort of interaction/engagement would they ideally offer?