Well, but lets say I have a cap of 15 happiness at the moment. If I stop growth, I'm capped at 15 worked squares. If I now rearrange my worked tiles so that I grow by two more every turn and my city gets to size 16, I'm still working 15 tiles and getting the most out of it. Right?
I can see the more maintenance I guess, but other than that, don't see how its a problem.
Edit: To clarify this more (because I understand what is meant about inefficiency), I make the assumption that I can't switch to another tile that will stop growth and give me any more production/commerce instead.