Moving any third party code to std library have both "pro" and "contra" and it was discussed several times. From my point of view there is nothing wrong with modules outside of std library as long as these modules are visible to newcomers, well documented and have developer support.
HTTP *very* important part in present time. Every modern language should have good native http-lib out of the box. I understand that it's can be done as outside module, but JSON also can be outside, and files can be outside. But I do not think that it's good idea.
http-request is much more friendly and powerful than curl. It's much better to move curl as external package.