https prevents MITM but doesn't prevent the modules being backdoored or otherwise altered at the source.
I would prefer https-only, sure, but it doesn't buy you very much security.
Well, diasabling http by default is basically "Internet 101" here.
I don't want to write an full lecture on how many attacks are possible when people don't use https. It has been commmon knowledge for way more than a decade
For instance, will a lockfile prevent someone from eavesdropping on the download of a modules through http? If so, please kindly tell me how!