I never really expected werebats to have anything added to them to make them more powerful, and flying in general is a whole other topic, because it isn't just MPCs that can fly or have wings.
Werebat's strength is their ability to fight aerial battles, and what I imagined using them for was targeted towards a lower level interaction. Having them fly would merely be role played out, and that's just as good too. We have an imagination, yay
I could understand the desire to make them more powerful though, they certainly may be lacking in something. All I could really assume will happen, for balancing, would have them hasted even in their Hybrid form to simulate that they are, indeed, typically in flight.