We use the textproto format extensively at work; it's super nice to be able to define tests of your APIs by using .textpb inputs and golden .textpb outputs. We have so many more tests using this method than if we manually called the APIs by in a programming language for each test case, and I wouldn't want to use JSON for test inputs, since it lacks comments.
Author here: Sorry that I was so harsh on textproto. You are right that it has some strengths over JSON... I'm actually a fan of JSONC for this reason. It does limit you on tooling... but so does textproto, right?
I think the bigger thing that I'm worried about is that gRPC has so many mandatory features that it can become hard to make a good implementation in new languages. To be honest there are some languages where the gRPC implementation is just not great and I blame the feature bloat... and I think textproto was a good demonstration of that feature bloat to me.
Yeah, the feature bloat makes it a hurdle to make some good quality implementations. I mostly stayed in Java for years. They are quite good. grpc-web is ok I guess, protobuf-ts are great, swift came along as nice, then I have always been saddened by how awful they are in Go. You will get terrible enums, terrible one-ofs, the interceptors and service registration are very awkward.
