I think they are referring to signed content, not singed transport. That is, this blob of content/code I downloaded is signed and I have more trust in it than

I think they are referring to signed content, not singed transport. That is, this blob of content/code I downloaded is signed and I have more trust in it than in some other piece of content/code that's from a server meant to house hundreds or thousands of different people, much less modules. You can trust that the developer meant to release that, and it's not some hack of the system, and you can also require that the code comes from a vetting third party that reviews all modules and updates and signs it itself (i.e. what Linux distro package managers do).