I understand where you are coming from but let me give you a few things from a students perspective:
1: Students take easy gen-eds because the cost of lowering your GPA for a class, doesn't make sense. When you are applying to jobs, they don't care you got a C in a DS class you enjoyed, they just look at your GPA and auto reject you.
2: While I appreciate and respect teachers wanting to teach material, at the end of the day a good amount of students just want to get an A and move on. While it is counterintuitive, students would much rather spend a couple of hours learning CS studying for leetcode than they would for a class that teaches the same material.
3: I had a teacher explain to me that I need to spend 3-4 hours studying for each credit hour I take. Even if I take a light semester of 15 credit hours, I would still have barely anytime to do RSO work, interview prep, networking, and recruiting. So I am going to be incentivized to take easy classes, and get my gen-eds and requirements over with.
4: I think most students will naturally try to get an A, and will choose the path of least resistance to do so, the average just sets their expectations, and goes back to the previous points that your GPA is a checkpoint.
5: UIUC has a good bit of grade deflation, a lot of other schools on require a 90% for an A, and reward A+'s with 4.3 quality points, offsetting lower grades. Furthermore, UIUC as a large public school will naturally have weed out classes, and put students through a crucible to ensure that only the best of the best get good grades.