Agree. As a Principle / Creative Director, I’ve seen first hand the difference between my creatives who went to design school, and those who didn’t. It has nothing to do with technical skills, rather the ability to present information and concepts, take feedback and understand process. No other place in your career will your peers and mentors be as open, honest and constructive to your creative and professional growth as in a good design program.
That said — I think that more designers should have a better handle on business, not the other way around.