I think compensation after 5 is reasonable, but compensation for anything a moment after 4 isn't. And I think that members have to realize that after 4 can mean AFTER 4. Which isn't 4:01. After 4 has been the communication for the entire 20+ years of my membership - it shouldn't be news to anyone. And then plan for "what if I can't get into the room until sometime after 4." That means having some plans - park, pool, minigolf, packing a carryon that will let you freshen up or change into a swimsuit, knowing where you are having dinner that isn't in the room, and scoping out somewhere young kids can rest - a resort quiet space.
Could Disney do better - sure - it might cost us more in dues. But we've been complaining about it for 20 years and they haven't. Spit in the wind if you want. I'd rather not get wet, myself. Hope for the best, plan for the worst.
That said, we've never had a room where the room was ready later than 3pm - and that was VAKL where we ended up with the worst savannah view possible. Most of the time our room is ready around noon or 1. Most of our stays at WDW have been at BWV (which is not the best resort for finding a quiet space for little ones to rest).