Assume I'm playing a race without buffs to razing. If my movement allows, why would I raze instead of sack + occupy + abandon settlement? Both end up with same result (razed town) but sacking nets both a lot more money and a tick of replenishment. The only edge case I can see is if you have stronger enemy army juuust barely within attack range so razing lets you retreat but being in a city wont. It just seems very suboptimal to raze most of the time.