As end consumers/target demographic of the web site, our impressions of the site ARE valid because we DO know their business of selling to us.
But you don't know their business. You don't know how well D&D Encounters is attended on the west coast vs. the east coast. You don't know which regions are buying books, and which regions only want DDI. You don't know what people click on when they visit the site, how long they stay, what the bounce rate is, or how sales were affected when the new site went live. You don't know if the 5e discussion has brought in new visitors, if that's led to a corresponding increase in new sales, and whether those people are buying PH1 or Essentials. You don't even know if D&D is making a profit or a loss. There's a million things WotC knows that you don't know, and hundreds that affect how they choose to design their website.
You know what you like, but you don't know their business.
Sorry to pick on you specifically, Janx. It's just that every D&D fan and his cousin seem to think they can run WotC's business better than they can. I'm just tired of it. I'd like to see less tearing down and more building up around here. Think you can do better? Great! Go build something cool. It doesn't have to be big. I promise not to tear it down.