I sometimes book from EWR, sometimes from JFK. I dodged a bullet here, as my flights in this period are all booked through JFK.
This construction would have taken away my margin of error for getting to these flights; I haven't missed a United flight in a million miles, and I don't want to start now. I would have requested that United rebook me from JFK; in my past experience they allow this kind of request. I wonder how many requests like this they'll field? And will this impact EWR upgrade rates?
I've experienced nearly all of the "alternatives" described on this thread, most recently forced to a $25, half hour taxi from Newark downtown station. On an earlier bus replacing the monorail, no one said a word when we were stuck at the locked gate till I announced this was a psych experiment. "Emergency Exits" is just a label, and this route could be opened; just staff the gate to keep out stray traffic. I suspect the real reason is that the area around the station will be tied up with construction traffic.