The reason I think it’d be nice to have in base would be so that a fast call to ghci would be able to get a hold of network access, instead of playing Russian Roulette with cabal install --lib (it’ll blow up in your face sooner or later) or putting up with delayed build times with cabal repl / cabal scripts.
The String precedent is also very nice as well; people complain about String all the time, wish that we defaulted to Text, but String implies it’s fine to have a suboptimal code in base and have people be expected to use other things instead for serious work.
Go at least has network libs in standard libraries, and given that Haskell is used a lot for backend, it seems reasonable to not expect learners or trial users to get a library to make HTTP requests.
That said, I agree that existing network libs are, while very mature, not mature enough, and there’s likely to be serious technological challenges because of the need for secure cryptography.
I guess it’s something the Haskell community doesn’t have the resources to do at this point in time. 