But also: why the heck wouldn't you want to encrypt it? The existence of leaks doesn't make basic prevention useless.
If you don't verify the keys, e2ee is basically meaningless against targeted surveillance. As long as some fraction of people verify keys, it is still effective against mass indiscriminate surveillance.
Generally, I'd argue that E2EE provides defense in depth against "unknown unknowns" if server infrastructure is compromised by any means. Although I do acknowledge it adds one more level of complexity, and often another 3rd party dependency (presuming you're not going to roll your own crypto), so it's not a strict positive.
Only if everyone's running their own personal homeserver, which seems pretty unlikely for regular people. You could've said the same thing about email (it's not meaningfully different unless your personal email server is compromised), but in reality the NSA ran mass surveillance on gmail and picked up a lot of data that way.
It isn't helped by the fact that the backup process is a bit obscure and doesn't work cross operating systems. For the select few that cares, verifying keys is effective against attackers who aren't Signal themselves, Google or in control of the Play Store. Just make sure to keep an eye out for that key changed warning, it's easy to miss.
And even if you own the homeserver, you still want E2EE since you don't want the data to rest in plaintext server-side.
However, there is work currently being done to make it feasible for every node to also be its own homeserver, via P2P Matrix (https://matrix.org/blog/2020/06/02/introducing-p-2-p-matrix).