> extracting arguments from the first line of an HTTP request.

The reason this sounds simple is that the use of “arguments” conceals a good deal of semantics. Yes, you can cut a huge amount of complexity out by using a subset of HTTP, and I do recommend that, but by switching to a “modern” rpc protocol you also lose a good deal of introspection, low-effort ramp up for new contributors, and highly replicated semantics on server and client side. You can debug or interact with curl (or a number of similar tools), or a browser, or any virtually programming language with many choices for implementations. There are tons of commodity tooling for log parsing, playback inspection, testing, fuzzing, load balancing etc etc. You get a lot for “free”, and the potential complexity by itself is a poor excuse for dumping the baby out with the bath water.

I also realize you may have acknowledged this by referencing “systemic” benefits, but I’d like to spell out just how large they are.