I don't use PMs often because I prefer to talk on the forum for the most part. My PM box is closed, so if you PM me it will say that I have elected not to receive PMs. I do have a buddy list though and I have elected to receive PMs from these people.
By the way, just because you're not on my buddy list doesn't mean I don't like you.
Like I said, I just prefer to talk on the forum. Besides, the less people that PM me means the less gossip and spam I have to deal with.