This one might be a bit controversial.gtkpacman hadn't been updated in over 6 years and hasn't functioned since pacman 4.1 at least, possibly before. I think it's safe at this point to say that it's dead. Dead + non-functional = should be removed IMO. Yes, it was a popular package with over 300 votes, but it's time is passed.
https://aur.archlinux.org/packages/gtkpacman/
