Assuming people adopt MCP then:

- JSON over the wire instead of binary

- Schema optional with the spec only defining the envelope

- Lack of inheritent support for code generation

- Poor support for flow-control or multiplexing

- Deadlines/timeouts, compression, per-call metadata, bi-di streaming, TLS, load-balancing hints: none of it standardized

- No inbuilt payment mechanism

Not understanding that businesses don't want open data or open protocols. Internet businesses want to monopolize information and charge rent for it. Capitalists don't want to commodify software, as that means lower profits and competition. They want to monopolize it. That's the whole game, except for companies selling physical goods over the Internet.