Honestly, since it probably costs them a lot to keep the parks open (in staffing) an extra hour or two .. I am surprised they don't cut back EMH more.
And really, I wonder what percentage of resort guests take advantage of that on-site perk? Most sites (like this) tell people to avoid parks on EMH days (unless you have hoppers).
I am guessing they will eventually do away with the EMH all together and just give on-site guests a free fourth fast pass. I would think with the way the crowds have been that that would be a more desirable hook to get some to stay on-site then having to get to the park super early or stay super late.
It would save Disney tons of money in staffing and virtually cost them nothing.
Besides, once they do away with EMH, it opens the door to them open the park early or late more often for more hard ticket events. "Mickey's Springtime Jubilee" .. "Mickey's Summer Celebration!"