If you want real security, you minimize externalized trust. By running your own server you do not have to trust anyone but yourself. And if the server is your own, you don't even need e2ee because in the threat model against which e2ee is helpful the offender is server operator. Replace server operator with yourself, and you remove the need for e2ee.
Of course, if you want a cozy sense of being secure, instead of real security, you say, 'I use end-to-end encryption which I was told makes reading my messages impossible'. With iMessages you can't really verify if your messages are not being sniffed (unlike Signal, or XMPP, I must add), and we now have proven Apple DOES have a potential way to read your messages if they really want it. But you TRUST them not to read your messages. So why bother with E2EE at all, if you already trust them not to spy on you?
(Also, how come people who religiously insist on using an always-on E2EE for their chats are totally fine with Gmail which stores every mail totally unencrypted?)