So you are saying that anyone having a requested room that was granted needs to arrive by 4:00? Otherwise that requested room should be given away? What if their flight doesn't land until 4:00 and they don't get to the resort until 5:00 or 5:30? I usually don't see a long line of people checking in at registration...people arrive at different times of day.
I think the issue is that if, say, 3 families are there at 4:00 then not having enough rooms to accommodate those three families is a problem. People are checking out at all hours of the day...it's not like everyone is checking our right at 11:00am and the housekeeping staff can't change over all those rooms. I realize the resorts are short staffed, but the checkouts are typically staggered. There should be rooms available for the early arrivers.
Personally, I haven't had issues with really long wait times. On our trip last week, our Poly room was ready at 11:00am and our BCV was ready at 1:30pm. This is the experience we usually encounter. The long waits seem to be the exception, not the rule. But if someone gets there at 4:00 and they have to wait until 5:00 for their room I think that isn't a huge problem. And in that instance I don't think a room that has been assigned to someone who requested it should be given away. That's just my opinion. I also see your point of view, though