I saw Linda's post about this when the decision was made over at the QIAD board. She said that subscriptions pay the printing costs, but all the other expenses and profit are in the advertising. Since they are in a position to know, I believe them.
If those advertisements in the magazines I buy serve to keep bringing me inspiration, new techniques, the words of amazing quilters I would never get to know of otherwise, plus new toys to look at and contemplate - and those same advertisements pay the staff to write, edit, shoot the pictures I drool over, distribute, etc. (who, by the way, like to earn a living wage the same as I do) - well, I don't mind so much.
If people keep demanding free, and are unwilling to pay for anything - I guess then it's nothing we will get.