Adding singleton to Data.List is a breaking change, when Data.Map.singleton was exported unqualified.
Data.Map's documentation states that the entire module should be imported qualified; this is not a reasonable counterargument.
RIO even takes the potentially-conflicting List functions out of Prelude, and puts them in a RIO.List module which is also intended for qualified import.
I'm +1. Personally I prefer `pure` and have TypeApplication enabled globally; but that's not a universal style, and I see no real cost here (though I agree it shouldn't be exposed in Prelude).
NonEmpty should get one too.