Agree with the previous posters. Grade inflation, yes. Broad admissions standards, yes.
But in a more general sense, it seems largely due to the (to me) bizarre notion that a good goal is for more people to attend university. U.S. culture nurtures the idea that if you don't get a college degree, you are worthless. Typical 'First World' wrongheaded thinking, the kind which Alexis de Tocqueville observed back in ~1835.
Which is kind of funny when you see many college graduates working (not by choice) at Starbucks or the like--just as you see see many non-graduates and even secondary school dropouts working quite ably and to great success in corporations or in businesses they themselves own.
The more I experience, the more I am convinced that--save for a relative few exceptions--people either have a basic grasp of thinking, writing, basic maths, etc., or they don't. Usually, this attainment or non-attainment preceeds the age at which one typically might attend college by approximately 10 years.