You don’t have to assume it’s about a lack of aid; Illinois is telling you it’s about price; why else the tuition freeze to try and alleviate the problem? Of course there are a variety of reasons (my kid is resistant for a lot of reasons besides money and he is a CS kid who should be over the moon to attend Illinois), but Illinois is telling us (as do counselors, consultants and anyone else who is directly involved) that a very big one is money.
Likewise, you don’t need personal experience re: Purdue because Illinois is telling us that falling yield is the reason for the tuition freeze. They are not talking about losing NMFs to Harvard and MIT; they are referring directly to neighboring state public schools, like Purdue which I just chose as an illustration, that are competing on price. This isn’t an anecdote in search of further examples, it is a postulate given by the school itself.
And Re: Business (kinda) and especially Engineering; These are the highest yield Colleges at Illinois. If every College were as well regarded as these, Illinois would not be stressing over falling yield, and we wouldn’t be having this conversation.
In the end, sure, there are many reasons to go elsewhere besides price, but many of those reasons are alleviated if the school did a better job of attracting top students. It’s a dynamic system. Attract the best students, makes school more desirable to top OOS students, makes the school more diverse and less of a same-kids-as-high school feel, which attracts more top students, which means less reliance on non English speaking internationals, which again leads to better students across more fields (instead of COE and Biz being the only schools for OOS students), which all helps turn the whole school into a target for top students and solves the yield problem. I know, sounds so easy, but money in the right places will get the wheels turning.