I did not read the whole thread but did look at the OP and the commentary on the first page and got an idea of where this was going (the same direction most threads on this subject tend to go) but a couple things stood out to me. I am not sure if any of my comments below were brought up but here is my take on a couple of call outs made by the OP with respect to marketing and the product itself.
Marketing) in the past the marketing as been targeted to males and featured male models in the advertisements etc... This was because D&D has been (and still is) a game predominately played by boys & men. Many data points indicate this is true including RPGA registration, community profiles (forums etc) and Market research. Research aside, our personal experiences have been somewhat different. We know females play D&D. We see this at game day events, we see this at Cons, we see it in our own games. So where are the female gamers and how do we reach them? Every survey I have seen shows the game is played by 95-99% males. Now you can get a false positive on the premise that D&D is game played by males by only surveying males but even in research that does not pre-screen for gender we either can't get a big enough sample of females to be relevant or the data supports the 1-5% female audience size. On the marketing front we have decide to not look at research, go with our guts, and concentrate more marketing at female gamers (and prospective gamers). We do PR outreach with media like
Cerise Magazine. Although we have not used live models in an advertisement for several years, going forward when we do real people (vs artwork) it will include at least one female. In fact last year we went through a significant casting process to find suitable female models for use in advertising.
Products & Product Development) Over the years there have been some very notable women that have contributed to the success of the D&D brand including (but not limited to) Laura Hickman, Margaret Weis, Michele Carter, Jennifer Clarke Wilkes, Julia Martin, Gwendolyn Kestrel, Jean Rabe, & Elaine Cunningham. The current D&D brand team is made up of 8 people, of which three are men (myself included). The VP of Wizards Brand & Marketing (my Grand- Boss) is also a woman. There are many people who work on a book throughout all aspects of the product development process, and a lot of those people happen to be women. I know this sounds a lot like , "I am not a ____ some of my best friends are____" but I just don't see us putting out an inherently sexist product. There are too many women (and men) on the watch for this to happen.
I don't buy the idea that D&D is inherently sexist. Fantasy as a whole has certain tropes that are sexist (EG damsel in distress saved by strapping barbarian) but we go a long way to portray heroic female characters as strong, independent, intelligent, without always pandering to the strong = butch stereotype. The D&D art style in both 3rd and 4th edition has made great strides to move beyond many of the old sexist tropes of fantasy while still maintaining femininity and masculinity where appropriate. Text is written in mixed gender pronouns (his shield or her sword) or gender neutral (their armor). NPCs are a mix of male and female characters as are their depictions in artwork. For example in the yet to be released Eberron Player's Guide on my desk there are 52 pieces of art featuring at least one humanoid. Of those 52 pieces of art, 26 feature at least one female character sometimes in a mixed group and sometimes alone. one note about this book is that it has a number of pieces of warforged art (warforged don't have a gender) depictions so the art is likely greater closer to 50/50. It is my gut that if you did this tally among all 4e books you'd see similar ratios in character depection.
For these reasons among others I just don't buy the OPs premise.