I have no problem if somebody has the money and wishes to spend $150 for 3 hrs in a mostly empty park and has the opportunity to meet rare characters. I can guarantee it won't be me.
I wouldn't even be to upset if EMH's were done away with, if that means that the park hours are more stable and more time is available for routine maintenance. I think the biggest cause of wear and tear of the parks and seemingly high amount of ride downtime has come from the strain of all the extra hours that the parks remaining open due to evening EMH's
Even though I am sure it wouldn't happen, maybe they could use the extra funds from these upcharged events to devote to maintenance.
Just go with the perk of extra hours that Universal offers (open 1 park each morning 1 hour early with limited rides operating), it would allow onsite guests the advantage of early access without causing undue strain on the park infrastructure.