Hi synchromesh,
That is a pity. A game does not need to run at 1920x1080 or upper resolution, it can be a bit lower, and probably the performance will be better in a lot of computers. If we forget about "old" resolutions, I believe would be a great idea to have the option to force a default resolution for GG games.
This can be a great way of game optimization. If someone from the community has any idea, please share it!