Why different dir for resources and cache?

Any clue why by default caches directories treat differently resources (images, assets, modules > inside the project) and filecache (getjson, getcsv > outside project, in OS temp directory)?

I have configured filecache to go in resources/_gen so that it’s easier to check/delete them from the IDE, is it a bad thing?

And also, why not simply use .cache instead of resources/_gen?