I'm a Graphic Designer and Illustrator. To me, I didn't think art schools were worth it for my pursuit, mainly because when employers see it, it doesn't reflect any other skills that may have been learned or touched on in general studies (i.e., core classes) and a strong Art dept. at a university would likely suffice anyways. I tend to view Art schools as high-risk (don't wanna sell yourself out if you are unsure about art as a career) and high-reward (you will possibly learn the most for your field you ever could from a degree program if the school is good).
Art classes in general, though, are 100% worth it for so many reasons. Even after graduation. That whole "self-taught" thing requires ambition and/or talent that is simply not in everyone at the beginning and taking a class does little to no harm to you in the grand scheme of things.
The biggest difference in having art for a career is that it demands that you have a strong skillset. Unlike other careers, you can't really afford to get by in the art or design world with substandard skills. Maybe in the commercial art world, but it's rare that anyone gets where they want that way. You have to possess strength in all standard areas. For me, those areas are various art software, web, and the range of imagery I should be capable of illustrating with accuracy or creativity. I'm sure this concept applies to other art fields, too. I can't imagine a painter being well off for not being good at painting drapery or gradations, for instance.
Anyway, the bright side of having an art career is that it sets the record straight for anyone who knows your profession: that success ought to come from pursuing your passion and working hard at it. Any time I tell someone I'm a graphic designer, they respond with excitement, but with a feint sense of admiration. I believe that's why.