The monorail station is too far away from all the Disney hotels to be used as transportation solely for them. I mean, when you are at DLH, you still have to go through security with everyone else coming in from the 2 hotels and Downtown Disney parking and walk to the station. It's not like you board the monorail on hotel grounds.
When staying at DLH, it offers a *slight* convenience into/out of Disneyland, but when staying at GCH, it's a longer walk to the monorail station than the front gates. It's not a benefit for GCH guests at all, really. GCH has the proximity factor to justify it's prices.
In addition the monorail now stops running at 7pm. Even before, it rarely ran after fireworks and was done for the night by 9pm, 10pm on nights with no fireworks.