Middle click paste is a very useful feature for a lot of people, but new linux users are not those people.
I personally switched two years ago, and got several people I know to switch too. Everyone I know who switched (including me) was confused by middle click paste.
It’s a hard to intuitively understand action (took me several months until I understood it took the selection for some reason) that is very easy to trigger accidentally, and that duplicates existing functionality.
The people who like it already know it exists, and could just toggle it on.
Of course, on distros not aimed at beginners, like say, debian, it should remain the default.
Honestly don’t know why people are up in arms and even posting about it. They aren’t saying they are removing the capability, just the default. Big whoop.
It’s Gnome. They do actually keep removing stuff that they disable by default, because they don’t even offer a GUI to configure these settings.
I’m guessing, those people are worried that it will be removed. It’s already somewhat on the line since Wayland started replacing X11, because individual desktop environments can now decide to implement it or not.