I would say they consider it a quality hunt because there is no general season in that GMU, and therefore the number of hunters is very small, compared to general season units. And the number of elk is much higher.
However, if it were up to me, there would be no separate "Quality" category, there would only be a bull category and an antlerless category. I see no reason for a non-quality bull elk category. People can decide for themselves what is a quality hunt. If it's not a quality hunt in my mind, why would I apply for it?