1) No. I think semver is just fine for its intended purpose. I mean, I'm sure its spec could be improved in various ways, but its fundamental idea seems fine to me. I think it's just important to remember that semver is a means to an end, and not an end itself. It is a tool of communication most useful in a decentralized context.

2) No.

3) See: https://github.com/rust-lang/rust-semverver --- But also, this is only ever going to be a "best effort" sort of thing. Semver isn't just about method additions or deletions, but also behavior.