Another thing to consider is that WotC is terms of new gaming products for D&D has pretty much stagnated. A lot of awareness for potential consumers of D&D comes from two places: book stores and friends who already play D&D. Go with me here. I'm talking about the immediate exposure of someone completely new to all things gaming etc, as these are the potential consumers who would be using Google to find out more about the game. Google would lead them to places like ENWorld and the main WotC website but these are more of a follow-up and not as high touch as the first two categories I've stated. Sure you could say that people Google things randomly all the time but there has to be a catalyst to cause theses non-gaming consumers to search the web for D&D in the first place.
Book stores, in my experience as a marketing professional, are the number one way that potential customers are becoming aware of the D&D brand, it jars their memory of it being referenced in popular culture and they can look at the books and look inside, and most importantly see the art which sparks the imagination and may cause them to buy the book or research it more online. (Never underestimate the power of art in marketing, especially with something so imagination driven like D&D.) The problem here is that since WotC has not put out any product lines of note lately many book stores I've been to and discussed with my gaming friends across the U.S. have seen their gaming section stagnate besides the regular flow of Pathfinder and few random rpg books here and there. Book stores see D&D as a joke right now, because the books began to sell so poorly. I asked a buying manager why they kept the few books they still had on the shelves at full price and he said they are just hoping someone comes in who needs an extra book for themselves or a friend. He said they have kept a small stock of the gaming aids, such as dice and dungeon tiles available but buying more 4th Edition books from WotC is out of the question, it's too much of a risk.
This leads me to WotC. I, personally am torn in two about the amount of time they are being allowed to develop D&DN. As a player and DM I want them to do a great job and bring D&D back to a hodge podge of fantasy goodness rather than such a focused design. At the same time as a player and DM (and this dips into the friends who play category) I am sitting in this void of no new D&D products (meaning D&DN) to speak of and thus I'm not interested as on the whole 4E either did or didn't do what my friends and I wanted it to do. Thus we are either playing 4th Edition D&D or we are not. We may be playing an older edition, but this hardly brings in google searches about D&D. We may introduce a new player to 4th Edition and that may generate some searches, but I think a majority (meaning 50.1%+) are not satisfied with 4th Edition D&D and are playing older editions which don't tend to generate searches or playing other systems entirely.
Note: I enjoyed 4th Edition for quite some time, but eventually it became to linear for me so I'm playing Castles and Crusades. But I'm sitting here waiting and waiting for D&DN because it will all always be considered D&D to me. ("Hey guys, want to play some D&D tonight?" When we are actually referring to Castles and Crusades or Pathfinder.)