The University of Denver argues for the implementation of Art into STEM for a couple of reasons:
It allows students to connect to the established elements of STEM in art practices, design principles, and assessment.
Although art may enhance a STEM student's understanding of principles in their field, STEM students have limited time and should focus entirely on courses that are related to their major. Additional art classes may dilute focus and cause worse performance in foundational courses.
Arts education involves the critical processes of creativity and innovation.
Creativity is an important part of STEM, however, the majority of the work is produced from already established concepts. We still use Netwon's Calculus and Physics from over 300 years ago; there is no need to reinvent the wheel.
The artistic processes of creating (presenting, performing and/or producing, responding, and connecting) are fundamental to student success across all domains.
STEM courses are objectively graded; there are right and wrong answers. Success in an artistic world is hard to measure objectively as much of it is subjective, and would not amalgamate well with STEM concepts.
Although there is a time and place for art, STEM and art have different objectives. Rather than combining the two, we should learn to appreciate their differences. It's okay for people to specialize in different fields so they can master their trades., rather than becoming a jack of all trades (and master of none).