That's interesting. On Firefox under FreeBSD+Plasma+Wayland, it does 1 if there's something selected, and 2 if there's nothing selected.So is it pasting the X11 selection or the X11 clipboard? Big difference.
Anyhow, I wanted to say that I don't like GNOME as a DE or the GNOME foundation as a foundation, but they have a point if the goal is to cater to the "average" user. Having the possibility of pasting by mistake something of value somewhere public is risky and better to be avoided. According to the opinion of this person who is I, changing the default of the middle-button click to "do nothing" and leaving the current functionality as an optional configuration is a good move.