If I'm in the business of making artwork that is designed on some level to sell a product, then I have to be very comfortable with the people I'm working with and I'd like to be proud of the end result regardless of its sale-ability.
It's hard for me to say what would happen if I didn't go to art school. It wasn't that I learned any specific painting or drafting skills at school that I felt I couldn't have taught myself. However there is something quintessentially unique and important that you gain by immersing yourself in ascholastic and creative universe, and being held to certain academic standards while being surrounded by artists of varying disciplines.
Drawing from art history and mythology allows me to connect with viewers in a familiar, yet loose visual framework. Blending disparate histories and themes can give the overall presentation a recognizable, yet unique flavor.