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 hate that its somehow different from ctrl v paste, that's what makes me angry more.
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)