While you would think that the idea of chain letters is dead, it is in fact still living on in the form of blog "memes". Bildo tagged me. But while I participated in such a meme once, I never really liked the idea. Thus I decided to go on strike, and not participate in this meme.
One contributing factor was that the meme wasn't a very interesting one. Come on! Couldn't the original author come up with something better than "4 jobs you had, 4 TV shows you like, 4 places you lived, etc."? Answering that feels like filling out a tax form or something. With a meme like "5 things you didn't know about me" you at least get a large degree of freedom what you want to answer.
Another thing is that you don't know who tagged you, unless you read that person's blog. No disrespect to my fellow bloggers, but I won't guarantee to anyone of you that I'm reading your blog regularly, and thus would automatically be aware of any tag. I read blogs in bursts, some days I read a lot of them, on other days I don't read any. I wouldn't want anyone to be disappointed because he tagged me and I never replied.
So I'm reserving my freedom to opt out of any memes I'm being tagged with, unless they are particularly interesting.