I think the solution is to really give the user control over when something is pasted and into which application. So if you press ctrl-V, it shouldn't pass that

I think the solution is to really give the user control over when something is pasted and into which application. So if you press ctrl-V, it shouldn't pass that on to an application that then gets to poll the clipboard, instead the OS or window manager should send the contents of the clipboard to the application the moment ctrl-V is hit.