That such a thing would be totally disruptive to CTF gameplay wouldn't enter their mind. Once such a change gets in, and people use it, the same people will complain that people build portals between both flags, and capture all the time

Also, note that such a change would break existing maps, that quite some people already like. So it probably is too late to change such things. However, it never is too late to add more options. After all, it's up to the mappers which weapons to place and which not.