Gnome devs don't like to give the user options.
I would submit that this is not a problem with middle click to paste, but rather a problem with a bad hardware design for the particular mouse you are utilizing. The true solution is to replace the badly designed mouse with a better mouse.
If the mice you're trying don't have those, and it's very easy for you to inadvertently press the middle button, then that does seem like a pretty major design flaw. If you're always buying mice from the same manufacturer, perhaps investigating a different brand is in order?
If getting better-designed hardware isn't an option, then I guess the alternatives would be improving your finger control so that you don't accidentally click the button while scrolling, or disabling it in software so that it doesn't matter. Honestly though disabling it and missing out on that functionality entirely seems like the worst of those choices.
The only time I ever intentionally use middle click paste is when using the terminal where, you know, Ctrl-C and Ctrl-V are already taken. An option to disable middle click paste for everything but terminal emulators could only be a benefit, removing a rare but ever present source of confusion and mistakes.
Opera does that, too, and I love it. No need to focus the address bar after selecting text, just click and go :)
But I guess if middle-click never does anything useful for you (Windows, Mac), you might prioritise it less in your hardware design :|
Option "EmulateWheel" "on"
Option "EmulateWheelButton" "2"
Option "XAxisMapping" "6 7"
Option "YAxisMapping" "4 5"
Which is exactly the way I scroll: Hold the middle button and move the trackpoint.