You're assuming everyone is coming to Rust from C. People who are learning Rust from a garbage-collected language will absolutely feel that Rust is harder than what they're used to, and not because they were writing bug-ridden code in Java or whatever.

Single ownership often introduces bugs of its own. In Java, I never need to create an Err if the thing my ID is "pointing" to isn't around anymore in whatever hash map the borrow checker made me store it in.

It's good in some cases, bad in others.