If you don't gain those critical thinking and analysis skills early on in your college life, how do you think you'd be able to do well on more advanced classes? Granted, it's hard to fail people nowadays, but there's no way most people in my department would give higher than a C+ to anyone with poor writing or analysis skills, content aside.

Incidentally, different people are good at different tasks. Some people are just naturally better at test-taking. That's likely the main trait that is tested by one-off exams. Do you think the ability to do well on such activities is necessary for good employees in most jobs?

In my current course, exams count for slightly under half of the final grade, given that I've been in enough classrooms to see that the people doing the best on exams aren't necessarily the people with the best understanding of the material (they do tend to be people who are best at taking exams!).