I don't blame ML or QP for not expanding service right now.
The province just brought in their new integrated fare system for the 905. It is reasonable that they don't make any irrational changes to the service levels until they see what the implications are for ridership. I also don't mean just total ridership but also the destinations, how far the riders are travelling, what stations they are going to/from, what times of the day they are travelling, and the impacts it has on weekend and late night traffic. They also have to allow the local transit agencies time to adjust their bus schedules to reflect the new realities
Everyone would be glad if they increased service right now but would be pissed off all to hell if, after taking in these potential impacts, the schedules for both GO and their local bus had to change again in a few months.
It may not be popular right now with some riders but it is a prudent move.