When you're at the theater or in the studio, working on your production, or in your space, dress however you feel comfortable and is appropriate for your work environment. I understand that often as arts professionals we end up doing multiple jobs, some of which may or may not come with the risk of ruining an outfit. It's important to wear something functional, but please, PLEASE, I beg of you: when you go out into the greater world to seek funding, or network, or market, or whatever, you are representing not only yourself, but your organization, and all other arts professionals.
Many people in corporate America have never met an arts professional. They don't get it, they're not sure what that means. Are you an artist? Are you a businessperson? The fact of the matter is that you are both, and your presentation should reflect that. If you're not dressed professionally, a traditional businessperson can't take you seriously, because they are trained that appearance reflects professionalism (or lack there of) in their offices on Wall Street & Park Avenue.
I know you're an accomplished professional and successful businessperson, so how about we show that to the rest of the world!
(both photos borrowed from db-oracle.com)