If you mean a shift toward pre-professional majors, that is probably related to the increasing cost of college. Students and parents are pressured by cost to consider how to prepare for immediate employment at graduation, in order to pay off student loans. Students not from wealthy families willing to support them in an extended job search may find it less attractive to major in something that has no major-specific advantages in the job market.
That said, many students choosing pre-professional majors (or liberal arts majors for pre-professional reasons) may not choose all that well either, in terms of considering whether their majors actually give much of a major-specific advantage in the job market, and otherwise making themselves marketable to employers at graduation.