I have included an aerial comparison of the area where you can drink legally at Jack Trice stadium and the same area superimposed (how fancy can you get in Paint?) near TCF.
I don't know that it's fair to make that sort of direct comparison when 75% of the space you have outlined is used for vehicle storage or is not suitable for actual tailgates. As I suggested in the tailgate thread here, the presence of vehicles is the antithesis of a vibrant gameday scene. For comparison purposes, see the Grove at Ole Miss, where the site is 10 acres, but hosts 25,000 people.
I know that Iowa State has a great tradition of tailgating, but it is not correct to assume that every acre of the site highlighted above is used for that purpose. For comparison, I have included Texas A&M and Alabama with the areas (to the best of my knowledge and recollection) that there are actual RVs, trailers, or proper tailgate tents set up as compared to the Iowa State "permitted tailgate zone." I could have included much larger areas had I included parking spaces where people either leave their cars or have a small grill and two lawn chairs, but I only did "real" tailgates.
From this image, it appears that the grassy area immediately to the west of the stadium is some sort of a slope, and would not really be a great place to set up a tent. You also see wide swaths of the parking lot with cars, but no real tailgates going.
I believe the answer is not to have an expansive area for tailgating, but rather a small, presigious tailgate destination free of vehicles like the Grove (Ole Miss), the Quad (Bama), or Spence Park (Texas A&M). Not to mention that Minnesota has about five distinct bar/nightlife areas immediately adjacent to their campus (stadium village, dinkytown, seven corners, etc.) where you can pregame (not to mention the campus itself, including dorms and Coffman). The area you highlighted includes Stub & Herbs and probably a dozen other bars. Jack Trice is a hike from the main part of campus and downtown, making tailgating the only real option for pregame food/drinks.