If the decor puts one off, I suspect the culture will, too. If we change it to attract some specific group, we should be careful that we are not attracting people who will not be happy here.

"CS is mature field and as such will do better if it projects a professional, neutral image" is a hypothesis, nothing more. Prove it with a successful venture -- but I don't think you will. This is still a place where passion trumps professionalism, and an enforced culturally neutral environment isn't the best incubator for passion.

Personally, I think we'll do best by simply being ourselves. And letting the demographic chips fall where they may.