Making Cargo.toml is annoying enough especially if we're factoring things out from an existing crate to a separate one: obviously we'll need to specify all the deps that the code is already using, and also possibly remove some deps from the old crate's Cargo.toml, and it can take a good chunk of time just to put it together. I mean it's nothing that we can't deal with, but it does slow things down for no good reason.

Copy over all the dependencies and then run something like this:

https://blog.benj.me/2022/04/27/cargo-machete/

Maybe something like that should be built into the Rust toolchain, rather than being a third-party tool?

Maybe one day. In the mean time, it is best for many people to invent many tools and then find out which work the best for the most people.

Agreed. Is there a community process for proposing changes and enhancements to the tooling?

There is, Cargo uses the RFC process for big changes just like rustc.

However, the Cargo team has been stretched a bit thin; back in April they added two new team members, and so things look like they're going in the right direction again: https://blog.rust-lang.org/inside-rust/2023/04/06/cargo-new-...