Users do not understand that E2EE means no easy device syncing and no serverside search, they just want to feel 'safe', but are not ready to perform such necessary things as fingerprint verification. And without verifying the identity of the remote party, E2EE is totally meaningless.

Telegram's far better UX than Whatsapp is possible because they do not have e2ee on anything but Secret Chats (and I've never seen anyone on Telegram using them). See, for most users the promise of security is better than actual security and all attached UX problems.