It diminishes the value of the park passes if one cannot use all purchased tickets to obtain FP. I don't really think of it as a loophole but exercising what was paid for. It also allows one person to obtain the passes for the entire party. Obviously FP+ would get rid of this need because you select your FP ahead of time, no running to kiosks, but I'd like to see it implemented where you select FP for the group, and first used for each time period redeems them. It's not screwing up capacity at all because the allocation is there whether it is the same individuals using them or multiple people. Its still a seat in a ride vehicle.
I am not saying you shouldn't use it with the way things are now....the loophole is there and there is nothing wrong with taking advantage of it; I am just hoping the loophole will be closed and for the reasons (quite valid ones imho) I have stated. :)