There are a couple I have in mind. Like many techies, I am a huge fan of RSS for content distribution and XMPP for federated communication.
The really niche one I like is S-expressions as a data format and configuration in place of json, yaml, toml, etc.
I am a big fan of Plaintext formats, although I wish markdown had a few more features like tables.
Your concerns are all valid, but about 1 and 3 there are possible solutions. I’m using Rust+Tonic to build an API and that’s eliminate the necessity of proxies and it’s very simple to use.
I know that it don’t solve all problems, but IMHO is a question of adoption. Easier
toldtools will be develop for it.