You do have to choose which packages you want to install at some point. When you do `npm install && npm start` it will still work as planned. The problem here address is for when you need to deal with a new issue.
If it were a handful of extra kb, I'd agree. Of the top off my head I can think of following file formats "somehow" suited for configuration: json, cson, properties files (java), yaml, xml, conf-files (Apache), ignorefile syntax, ini files.
Supporting all of them could be a reasonable goal to the community (looking at the packages in npm: it is an actual goal already).