Your poor judgement on taking the city and you can't be much better if you have 10 cities on an island!!!
Obviously that's an exaggeration. But this solves a lot of problems. For example,
if you're playing in a small team and you're unable to close islands ---> Take and raze
someone is spamming you with a small city from an undesirable location ---> Take and raze
you don't want to take rock cities as its domination end game but a salty player founds on one to annoy you ---> Take and raze
you suspect an enemy of using an alt account to boost or favor farm ---> Take it and raze it
If taking cities is the most important thing in the game, you should have more options with what you can do with the city once you take it. It doesn't change anything per se, it just adds another option