Retaining knowledge is no longer necessary because we all carry the Internet in our pocket. Most schools teach the test and that's about it. If you're not brought up in a house where reading and understanding information is modeled, there is almost no chance that you'll pick that up in another environment. I always laugh when people research the 'best schools' for their child. All you have to do is look at the average educational attainment for the school's attendance area and the schools will show up as the 'best' (not saying that there aren't awesome teachers who can do magic, but it's an exception).
What troubles me most is the lack of critical thinking skills and logic.