There are several challenges in studying popular culture. Let me name a few of them.
First, popular culture constantly changes. For this reason, the study of popular culture has to constantly change as well. No one can rest on their laurels and presume to master a topic like popular culture.
Second, frequently popular culture emerges from small underground movements. Hence, it is very hard to know what the "new" movement will be. There is very little a person can do to anticipate what the next big thing will be.
Third, popular culture is often not valued as a topic of serious study. So, the best minds of the academy rarely spend their time in examining popular culture. For example, you cannot major in popular culture in college.