I've written in a lot of different places (like here and here) that I was not the best undergraduate student: I didn't come to class, I was distracted while in class, and was more concerned with the social side of university life than the educational side. I selected my undergraduate degree because it offered paid semester-long internships in my area of study (professional writing); as long as my GPA was high enough so I still qualified for those internships, then I was fine.
This was not the fault of the (majority) of the wonderful professors who taught in my program; if not for them being just generally great, great teachers, I wouldn't have stuck around to do an MA with them. Sure, there were some duds, but over-all, the quality of my classes was excellent. Could they have sat me down and said, you're doing well, but you could be doing so much better if you just applied yourself (code for actually showing up to class and not being hung over)? Yes, but I give them credit for treating me like an adult and letting me make my own mistakes. Thankfully, because I got good grades, I could learn the life lessons without being forced to drop out, like some of my friends.
No, the fault lies with me. What I learned in college was about life, who I was, and who I wanted to be. I knew, pretty quickly, that I didn't want to be a technical writer, that I loved literature, and I loved to write (not bad lessons, really). I learned how to budget (the hard way), I learned how to (minimally) cook for myself, and I learned that sleep was really important. I learned that I wasn't indestructible or immune from failure. I learned how to recover from said failures; I learned resiliency. Or, perhaps I learned more ways in which I was resilient. You have to have a certain amount of resiliency to survive high school, divorced parents, and participating a competitive sport. Now I knew I could survive other situations as well.
I did develop my critical thinking skills, but mostly through my immersion in another culture and language; I went to a French university in my home province of Quebec just after a referendum. I also improved my writing and research skills, and I was "forced" read books I would not have ever read (or understood) otherwise, even if it took years to come around to them again as a professor. I'm not sure, however, if I would have self-reported any of these developments in a survey or if they would have shown up in a test. My brain, throughout a lot of university, was elsewhere. I remember almost failing a French grammar class because I was unable to answer basic questions whose answers I had known throughout high school and know once again today. But in that moment of my second semester, I didn't know anything about French grammar. And I was trying.
What I learned as an undergraduate directly shaped who I am personally and professionally today. I just don't think that if you had told any of my professors back then that I would now be teaching at the university level that they would have believed you. Just because an undergraduate doesn't look like or even recognize themselves that they are learning anything as an undergraduate doesn't mean that they aren't. Maybe it just means they haven't realized it yet.