Haskell started out with a completely flat namespace; a minimal and minimally disruptive "hierarchical" namespace was added, without any special semantics and without any intent to define such semantics.

Haskell does not have the concept of modules as containers that you seem to have; it never has had them; and there are ongoing and unresolved arguments over whether some ML-like module system should be adopted, so it's unlikely that they would be added in the absence of such resolution.

You apparently believe such a thing is implicitly part of namespaces and that we need some reason to not have automatically created them to your specifications.  Could you explain where you got this notion?