I am more sympathetic to your concerns than I came off as at first. I have just seen time and time again friends and family asking me to install a wireless system because they think their abode is uniquely unwireable. And without fail these situations end with people having an unreliable (if ever present) or not as capable network as they would like. This usually leads to either people who resent the entire existence of networks (I know it sounds farfetched, but my various people I have "helped" would back me up), or they end up biting the bullet and wiring the abode. I find that in these situations the very unwireable situation is usually resolved easier (and cheaper) than the maintenance of a wireless connection.
Then we have the secondary bias, I may have been raised weird, but I have a keen understanding of the use of the words want and need. Call me unsympathetic if you must but your 10 yr old with a laptop does not need to be buzzing around the room like a honeybee. I used the word need in my statement because I understand it is a wonderful convenience for spontaneous and unimportant usage. I do use wireless at home, however I don’t need or rely upon it and I do have a piece of CAT5 laying next to my bed for use with my laptop.
As for marketing, that’s a bit outside my reach and I am certain the previous poster had it right that it works for D-Link in the lab, but hard to wire houses make for hard to wireless houses.