A better idea would be to replace / improve the fetch spec. Handle redirects, set JSON as the default request content type, encode URI components for users, decode response bodies with JSON headers as JS objects, etc.

Right now most developers either write their own library to do these things on top of fetch or another HTTP client or use a third party library from npm.

A new standard would allow us to make http requests out of the box comparable to high level HTTP clients like superagent, axios etc. that have been in use for the last decade, since before fetch was conceived, with whatever benefits fetch provides (I think it's cancellable now?).