I like the forums better than the blog for many reasons - writing style, for starters.
As for the forum (which I lurked, then joined & still lurked and then finally started to post) - Pete (the person, not the MMM persona) has created this "meeting space" that is free for me to "visit" and get all sorts of ideas, learn more, share what I know, and support (or give support) to other people who may share some common values or goals with me in reducing consumerism, saving money, or just plain making things BETTER for themselves, however they define it. There are lots of ways to be, and I get good ideas and confidence from seeing that there is no "one way" to be frugal or enjoy life or reduce consumption or earn income or whatever.
I appreciate what I get out of the forums, even if Pete has monetized his site such that I'm more like a bar patron or tv viewer than a living room guest. If I go to Cheers because I like hanging out with Norm and being insulted by Carla, that doesn't mean I agree with everything Sam thinks, especially if no one expects me to buy a drink!