I agree that grass does not work well for a hugely attended festival such as the stampede. Every large festival site for events similar to the stampede looks like a giant eyesore when they don't have events going on in the area. For a comparable, this is the Oktoberfest grounds when they don't have an event there:
https://www.google.ca/maps/place/Mun...!6m1!1e1?hl=en
The Stampede is working on upgrades for their grounds, but I agree that they have been slow at implementing. I believe the Enmax park area should be opening next year across the river. The Indian village will move to that grassy area at that point opening up more grass in the area. There are plans to move the coke stage to a larger area and expand the grounds north in the future, but your guess is as good as mine for when it will actually be fully implemented.