Toward a "modern" Emacs

The licenses you have on a piece of software set the requirements you have for distributing that software. You can argue an implied license, but arguing that it's okay to copy a whole work with no possible fair use argument just because you don't think you'll get sued is simple piracy.

In the case of Linux, like any other work with so many copyright holders, it's clear that at least some copyright holders don't agree with this implicit license, even if they don't always have the will to go through with a court battle. That's why we have explicit licenses, so all the copyright holders on Linux can get together and agree on the terms.