It seems to be existing only because of the current popularity, it stems the priority queue, therefore allowing the priority to remain a priority and the normal queue still actually move.
Or would you rather all passholders use priority, then slow the main queue to zilch so they have prejudice against them just because they're an on-the-day paying guest/tourist?
It has to be balanced out to be as best as possible for both worlds. Not easy decision, but one I'd agree with. Remember priority is like fastrack, and you're all for cutting fastrack users.