Betaar: I don't think of it that way. Even charity organizations do it that way and it is a win-win proposition. It isnt only about making money always but also letting people wear their interests. Selling merchandise is not BC's primary focus anyways. I have seen other Forums doing it too like DeviantArt.com, Mozzilla, 2600 etc. Its a matter of showing someone's interest and promoting a brand as well... my 2 cents.
Bangladesh_sy: I have personally done this for raising funds for cyclone victims where we designed and sold T-shirts. Being Bangladeshis, we thought we will be not be able to sell these 300 Hanes T-shirts. But to our surprise, we were not only sold out, folks wanted to get more,, even when they knew that the $19.99 t-shirt actually cost us $3.95. People just loved the T-shirts and wanted to donate for the cause..