I think I mostly agree with you about what namespaces should do for us, but somehow I end up liking Rust's choices and you didn't. Interesting.

I like that core::cmp::Ordering and core::sync::atomic::Ordering exist because in their contexts I think these types should both be named Ordering and so it would be annoying if they were named Ordering and AtomicOrdering or something. If I'm writing code which does tricky atomic operations I can bring in core::sync::atomic::Ordering and now Ordering means that one, whereas if I'm writing code about whether this Goose is before or after that Goose, I ask for core::cmp::Ordering to get the relevant Ordering.

And if it's unclear in context, I can write core::sync::atomic::Ordering and everybody knows which one I meant.

I don't usually use an IDE but I believe it's usual in an IDE to tell you the full names of such things and even to help you import relevant stuff based on completions.