I don't understand. Rust 1.0 code will compile on Rust 1.14, in the same way that C code from the 80s will compile on modern C compilers. That's what "backwards compatible" means!
Your dependencies don't upgrade themselves. Its true that if you upgrade your dependencies, they may depend on a more recent verison of rustc, in which case you need to upgrade rustc as a part of upgrading that dependency. But if you are using rustup this is not harder than upgrading those dependencies - probably easier in fact.
In exchange for downloading a tarball at most every six weeks, you get a language that is developing new features.
Your dependencies don't upgrade themselves. Its true that if you upgrade your dependencies, they may depend on a more recent verison of rustc, in which case you need to upgrade rustc as a part of upgrading that dependency. But if you are using rustup this is not harder than upgrading those dependencies - probably easier in fact.
In exchange for downloading a tarball at most every six weeks, you get a language that is developing new features.