I'm not a subscriber, but I can echo some of the thoughts already expressed, to explain why I'm not, and possibly help shed some light on what others might be feeling as well.
* I just don't subscribe to online services. Especially message boards.
* The quality of posting on Enworld has declined dramatically in the past few years. Blame that on edition wars if you want, but the overall tone of the site and so many of the threads here now are bitter, spiteful, and combative, no matter what the topic.
* I don't play 4E. The support and focus on 4E isn't something I'm going to pay money for. I understand its the current "official" edition, but its not my game of choice.
* Enworld has been very pro-WOTC, which is fine, and perfectly reasonable, but sometimes it veers into the territory of DRINK THE KOOL-AID! Or, sometimes seems very heavy-handed in disallowing any criticisms of WoTC, even legitimate ones.
* I know Enworld offers a lot to the community, and it has been an excellent resource in the past for the overall gaming community, a truly top-notch site. However, I just don't feel comfortable forking over a monthly payment to a site that's changed so much, so a guy can make a living off of what is essentially just a fan-site.