This question has always bothered me while playing League of Legends. If I win my lane and take an early turret, I give myself the opportunity to roam at the cost of letting my opponent free farm their lane. While roaming benefits my team's other lanes, it also allows my lane to be counter-pushed and the turret taken.
However, if I choose not to take my opponent's turret, I force them into a somewhat dangerous position, as farming now leaves them open to ganks. As a counter point, though, doing so forces you to stay in your lane, lest your opponent push it and take your turret.