How about that, so does my bank. I'm only allowed to use letters and numbers. I forget what the length limit is, but yeah, short for that kind of simple password. I have much better passwords for forums.
allsorts asks, "Why?" The only thing I can can come up with is they're too lazy to write the regex.
I've been railing about this for years, but since we're on passwords: Password Manager. They've had a decent one in OS X (Keychain) since at least 2002, which is how far back my saved passwords go. Since I began using it, and began creating unique and complicated passwords for each account, I've never had an account compromised. The only one I worry about is my bank with it's enforced simplicity.