The current standard library urllib is a refactoring of previous attempts from the 2.x standard library, and urllib.request is just a sub-package. It does not represent adoption of requests; requests builds on urllib3, which was created to fill in gaps in what the standard library provided, and named like that because the 2.x standard library had both a `urllib` and a `urllib2` as they struggled to figure it out.
For a long time, urllib had everything deprecated except for the parsing code which remained relevant as the upstream RFCs have not changed IIRC.
Urllib2 is now also gone and mostly replaced with urllib.request.
It should cover 99% of the use-cases one would use requests for — I am not sure how and why it matters that it is a subpackage and not a top-level package?
This is just a natural evolution of a widely used language where you have to be careful with backwards compatibility.