But which are you more likely to do? The above scenario only happens if you miss a FP, then want to wait again, for another window. A bit more decision making there. No different than what many people (that didn't know about the loophole) had to do before. It's much easier for you to just grab FPs earlier, and use them as you wish, deciding later. Now it's a bit harder for someone to easily do this. If they missed a FP for legit reasons, and grab another later, so would people who just want to ride the ride again. That's not an exclusive club.
It will result in fewer FPs being pulled to begin with as people realize they are only good when they say they are good. They've removed the incentive to take a reservation for a FP return time when you know you won't ever actually return at that time. This leaves potentially more slots for people who would.
And while some may miss a FP return time, then get another, that already happened before anyway, at best it's a net zero. But more likely it's less FPs a person pulls per day because of the restrictions involved.