Twitter spends more on R&D as a percentage of sales than 5 other large tech companies, even Facebook, and moreover, the percentage is increasing. Where is this "innovation"?
It's not a new platform. Its market is, arguably, saturated; I don't see a "next billion users" (as they say at Google) coming from anywhere.
So the answer to "If there is a major exodus, will it even matter?" is pretty clear: No, as long as it's not the operations people.