This is just a rehash of the old, "who is more important, the engineer or the marketer?" argument. If the marketer has nothing to sell, he's not very important. Likewise, if the engineer can't bring her work to the world, she won't be successful.

I look at good web design as a branch of marketing: you are branding your product and making it known. Great marketers are extremely valuable, yet there are also people who call themselves marketing experts who don't really understand what marketing is all about.