I believe the internet was the main culprit. Any information you wish to have, is available 24/7, with just a few clicks away... why wait a month or more for the magazine, when all the information you need is available now. By the time you receive the magazine all the "news" will be "old news". Unfortunately we live in a society hungry for information...
When I was younger I used to love to visit the bookstore and anxiously search for the new issue of EGM. I had tons of the early EGM issues, and I remember an editor going by the name of "Quarterman" if I'm not mistaken... I loved his articles. Those mags got lost or thrown away... I should have known better and kept them for posterity .. :(