Protobufs and similar projects like it (gRPC, Cap'n Proto) seem really interesting, but I haven't come across a time at work yet where it's made sense to the team to adopt it. Maybe that's just my own inexperience, but the serialization scheme is low on the list compared to optimizing DB queries, getting rid of bloat in the app, etc. I've been waiting for an excuse to adopt this stuff at work because it seems really cool!