We typically can ride maybe 3 or 4 rides before DS gets overwhelmed and asks to leave. The rest of the day, one of us goes back to the room with DS and the other remains with DD. So for those few rides, we can experience them together. The rest of the time, DD and one of us wait in the lines. I hardly think that's overuse.
The policy was changed because of low-lifes that abused it. Not because the system was overwhelmed.
This is untrue. It was changed because of over-use. Disney has had several news articles you can look for that state "the system had become unmanageable". I'm not going to bother to find them for you but they're out there. Actually you can probably just google GAC and the system became unmanageable.