You say you wanted to make the most of your last day at WDW, well, so did they!! It's not bad parenting, it's making the most of having to check out of your hotel at 11am, plane doesn't leave until late, no place for "down time," etc. From your post, I assume you don't have children and have never been in such a situation...until you have kids, you have no right to judge ANYONE'S parenting skills!
Actually, I disagree. If you know you are going to have an evening flight and you have little kids, then don't "get up at the crack of dawn" and keep your kids "going all day". The results are entirely predictable and you really do NOT have to be a parent to know that it is going to result in tired, cranky kids. Also, any parent knows that there are ways to make downtime when downtime is needed even at Disney or in an airport. I do have kids, I have been in that situation and I agree that the parents could have made better choices. However, in deference to the parents in this situation, perhaps they didn't choose that flight and their original, more appropriately scheduled one was cancelled.
taitai