It is a preference - and not everyones. I always hated middle click paste, middle click is amongst the first thing I remap on my systems to do the macOS "exposé"-style of window rearrangements. Other people will have other preferences.
I suppose you use Super+Middle Click? Not a bad idea, I dislike hot corners, and the "exposé" feature of niri is quite good. I might actually remap it to Super+Middle Click.
(I use Super+side mouse buttons to move between workspaces, I hate the keyboard-centric workflow when one hand is always on the mouse)
I don't use Super. Middle click (Button 3) = expose, Button 4 = workspace to the left, Button 5 = workspace to the right. Requires a good mouse with accessible button 4/5 of course. No key modifier.
No software I use, uses these buttons for anything integral by default, neither on Linux nor Mac. And if they do, the OS has precedence. On macOS I use BetterTouchTool for those mapping, you can define exceptions for individual apps.
That's what some people love about it. Gives them 2 clipboards. Personally I think copying into a shared space without an explicit action to do so is terrible from a security perspective, so getting rid of middle click paste by default is good to me.
