Disney's Magical Express does not wait for the buses to be full. They don't do so now, and they never have since the launch of Magical Express. They may wait a while for more guests going to the same resort, but there's no requirement for the bus to be full.
Often, buses are dispatched with more than half the seats empty, because it's time to go.
There is no reason to believe that the Magical Express product has been degraded due to the economy.
Full? Maybe not completely full. But, the last two buses I have ridden on, have sat there, for half an hour, waiting. In Sept, we were among the first to board the bus to POP. There were maybe 12 of us on the bus, when I got on. But, we sat there, for 35 mins....no, there were no people in sight...the driver just stood outside, chatting with other drivers (whose buses were also less than half full!). Guests would come straggling along, get on board, saying..'This is great, now we won't have to wait as long since there's no one else in line waiting to get on!!'. Ah, no..not happening. From what I understand, on that one trip, the total time waiting was about 45 mins...that's what a passenger told me when we finally left. She was the first one on the bus and just couldn't figure out why she had to sit there for 45 mins!!!
I truly believe that if they start cutting back, there will be fewer buses/drivers. If that's the case, you won't see buses leaving half full....that wouldn't make sense. Even those riding the buses after 9:30/10pm have to wait much longer than those riding the bus midday.
Those buses are not running every 20 mins anymore...and I have yet to see one pulling out that didn't have a good sized group in there. It just doesn't make sense to send out two buses, within 20 mins of each other, that are 1/3 full...makes a lot more sense to tell guests that the buses leave every half hour..that way they can put more people on each bus.
So, I will respectfully disagree....more buses are waiting to get more guests on board before leaving. Full? Maybe not full but a heck of a lot more people than they did a year ago!