So the rest are actually OK with Whatsapp/Signal having the opportunity to see their messages? I would submit that most are not even aware of the issue...
The identity thing is basically the usability issue for E2EE messaging. If you don't solve that then you have not actually increased usability in a meaningful way. The PGP community understood this and did things like organize key signing parties. When is the last time anyone did anything like that for any popular E2EE capable instant messenger?