The main thing I dislike about using G+ is that it removes spontaneity and requires zig-zagging all over the park and having to stick to a strict schedule to get the most out of it. My family then hates me for marching them around and not leaving much room for that oh so important exploration and discovery.
From the perspective of the overall impact it has, it is amazing how much more quickly standby lines flow when G+ shuts down, at the end of the day for example.
They will likely never do it because it is such a cash cow, but my preference would be for them to do away with it entirely. Until then I almost feel required to deal with it because if I don’t I am being impeded by everyone who does.
Would the standby wait times for the most popular rides get longer? Maybe to some degree but there is an opportunity cost to standing in line and the bigger the differential there is between the apex attractions and the tier two rides, the more likely it is that people will pass by for the shorter line. If it is worth it to them to eat more of their park day to ride that particular ride, then so be it - the longer they are in line, the less they are making lines for other attractions longer. If someone wants to stand in line for 8 hours to ride the 60 second long Tron, more power to them, but in the mean time that is one less person riding all of the other MK attractions.
Might be an unpopular opinion but I think having line skipping gone would be a better experience on average. Sure those waiting in those long lines for the few top rides would probably say otherwise, but at the end of the day that was their choice.