I hear you but as the owner of a C-14 with rusty bolt heads in those wells, I think the covers are a great idea and would like to re- use them. I looked at just buying new ones but at just under $4 each, that is a bit to much to be disposable. My handlebars tend to be taken off quite a bit as I am working on the front of the bike.
I will try a shot of compressed air but otherwise am still looking for a solution....
Mine are long gone. I could not really get them out without damaging them, then lost one, then it just wasn't worth it. I suspect most will tell you the same story.