I've done a bit of googling, and while I was probably not exhaustive in the combinations of terms that I tried, I haven't been able to find any studies that show a decline in the overall intellectual curiosity of graduates from US schools.
I'm not saying that I know it's not happening, I would just like some help finding said studies before I take a position on whether there's any over-arching intellectual collapse going on right now.
As to the broad spectrum of targets, considering the number of times people have tried to blame evils on "bad rock and roll", "violent video games", and high fructose corn syrup, I only willingly apply blame to targets where strong studies have shown overwhelming correlation and a possible (preferably a strong) causative link between the effect and the supposed effector.