It doesn't seem that complicated to achieve with IP addresses listed in a nip65-like event for relays and pubkey support in nip65 events.
I doubt clients would see implementing it as a priority.
It would be a fun project to make a PR for it in 20+ clients. 

 Yep, it's really easy to setup. Then relays just need to accept connections via IP directly. We could start with just wss://<IP> if they want. 

 I noticed you have talked about it quite a lot. Have you had many objections to the idea? 

 Not a lot for the relay part. But I started the no DNS pitch with static content (that shouldn't use http addresses as well) and the criticism for that was through the roof.