> What's the point? How is typing foo::bar better than typing foo_bar?

You're missing the whole point of namespaces. The goal is not to replace foo_bar with foo::bar. The whole point is that within a scope you can type bar instead of foo::bar, or bar instead of foo::baz::qux::bar, because you might have multiple identifiers that might share a name albeit they are expected to be distinct symbols.

https://en.wikipedia.org/wiki/Namespace

> What's the point?

using namespace kind::ofa::long_name;

or

using kind::ofa::long_name::bar;

is the point.