The typical interface for handling merge/pull requests adds so many useful things over just sending a patch - if the project has CI I can immediately see if it even successfully builds before even going into the details of the PR.
Same for reviewing, each comment can be replied to separately or resolved, which serves as a nice TODO list for the original author.
I know there are some things people don't like (I think Linus was pretty vocal about it), but it seems to be they could be easily fixed by modifying the available open-source forges. This proposal here for example fixes the concern about centralisation, so I guess it's a good step forward.
Or maybe I'm just young and like shiny things and will eventually have a spiritual awakening and learn about the virtues of sending in patches via email.