I should think it would be obvious it wasn't this easy if for no other reason than the relatively recent ability to use Rune Shards to donate KP. That revealed a mechanic that's been in play for a very long time to help prevent cheating - namely, donation caps.
If you don't think mucking with how much KP you have instantly in a wonder on the back end isn't going to completely destroy your ability to receive KP donations to your existing AWs, then you are thinking far too simplistically. And that's only one variable component that Support would have to be cognizant of in putting an AW back into a city after accidental deletion.
There's a reason that "coder time" is one of the things we're supposed to be aware of when making suggestions for changes in the game.