There is the argument less is more, but DW are consistently putting on additional events every school holidays (that are free with admission), while across the road only do it in Summer and Easter. While I would agree the quality of these events might not be the same as MW's, at least they are offering something 'extra' for locals and tourists.
If these overlays weren't on, would we miss them? Probably not, but I'd rather have something than nothing. That's providing it doesn't detract from the everyday park experience, which I don't think they do.
Most of these overlay events have been happening for a couple of years now, so there will come a time when they will need to mix it/refresh them, but that applies to every event at all the parks (looking at you Carnivale & all Halloween events)!