Buck's right... the usmle board exams are some of the most important exams medical student/doctors will take in their career. Because course grades differ from one school to the next along with the quality of education one receives, you really can't standardize them and say that a 4.0 from Buttsky U is better than a 3.5 from Harvard Med. Kinda like the SAT, ACT, MCAT, etc, the usmle is standardized so everyone has more of a fair chance of showing what they know compared to everyone else.
And like Tulane said, Step 1 is most certainly the great equalizer. People who get through their first two years by rote memorization and cramming are going to be at a huge disadvantage come Step 1 as compared with people who don't cram and memorize for their A's. I personally know someone in my class who is making A's in all his courses so far, but I've tried to talk to him about information in those courses, and he doesn't have a freakin' clue. He might be smokin' right now, but I have this feeling that the Step is going to stop him dead in his tracks.
The Step exams test the way you THINK, not how much information you can just memorize. Most med school courses (I'm sure there are some exceptions) test how well you can memorize tons of information and regurgitate it all on a tests. Smart thinking and analysis is what is going to make you a good doctor, not how much information you can memorize and dump over a few days. Think about it, what good is all this information going to do you if you don't know how to apply it? I think this is the nation's rationale behind the importance of the Step exams as compared to individual school grades
