It could be that our colleges haven't done a good job of keeping up with technology. For example, using a library to write a paper was far more challenging and limited than using the internet. We can access a lot more information faster. Schools would need to adjust their structures to achieve a similar rigor.

They also accept a broader set of people now, some of which perform better academically than others (statistically).

But yeah, it could also be that standards have lowered. It's hard to tell without more data.