Also, even if you do want to have some kind of binary-ized transport with a strict type-checked schema and compilers for multiple languages -- ultimately a noble goal, I think -- there are much better options available, design and technology wise. Cap'n Proto is wonderful with a very strong foundational design and good implementation, it's major drawback being a relatively sparse set of working languages, and a lack of tooling. But then again the quality of 3rd party Protocol Buffers libraries has always been a complete gamble (test it until you break it, fork it and patch it to make due), and as you note the tools aren't all there for gRPC either.

So in general I completely agree. If you are exposing a Web API to consumers -- just keep doing RPC, with HTTP APIs, with normal HTTP verbs and JSON bodies or whatever. Even GraphQL, despite having a lot of pitfalls, and being "hip and fancy", still just works normally with cURL/JSON at the end of the day because it still works on these principles. And that matters a lot for consumers of Web APIs where some of your users might literally be bash scripts.