Carol is right. Student evaluations are doing a great deal of damage to academic standards. With the retention of students being the top priority at many schools these days, and bad evaluations indicating student unhappiness, the inevitable result is pressure on professors who get bad evaluations to shape up and make their courses more “user friendly.”
A book that nailed this point is Generation X Goes to College by Peter Sacks (a pseudonym). The book is now a decade old, but the problem has almost certainly gotten worse as the high school graduates who are recruited into college become generally less inclined toward serious academic work and more prone to insist that “education” should be fun and easy. Pandering to such students means that courses become mostly a waste of time for the good students.