I realize most folks don't make early flights, but what really aggravates me is the late evening flights. I usually try and get the latest flight out possible, which in some cases has been as late as 8:30pm, which means I have to hang around the resort till 8:30am to use resort airline checkin. If it was open for a few hours in the evening, that wouldn't be necessary and wouldn't kill the entire morning. We are ALWAYS out by 6:45 each morning.
The problem is the 12 hour rule. Your option is to have breakfast in your resort and check your bags at 8:30, (I suspect that's what most guests would do). Put your bags in storage and come back at lunch time. That could work if you were staying at a resort near a theme park. IF RAC extended their hours your third option would be to return to your resort at least an hour earlier than you otherwise would have to. You have to check your bags 3 hours before your flight and DME picks up 2 hours before your flight.
I see your point, but I doubt there are many guests in your category. My guess RAC would wind up having to refuse bags from the many guests that didn't make it back to their resort early enough.