1) My password doesn't really suck. It may not contain any numbers or special characters but it isn't a name or even a real word, so it's unlikely to appear in any dictionary, thus making it pretty uncrackable by brute force.
2) If I want to have a crappy password, that should be my business. What does LJ care if my journal gets hijacked? What damage can a hijacker cause that any anonymous LJ user cannot?
3) My LJ is not important enough for me to care about password security. If someone did take control of my journal, they would hardly be able to screw up my life, or commit any serious crime, or do anything worse than make some stupid posts/comments in my name. In short, I wouldn't really care if someone hijacked my LJ, and if they did I imagine I wouldn't have too much trouble getting it back (although the same may not necessarily be said for non-paid users who haven't had that level of official contact with LJ admin that they could use to prove their ID; but if you don't have a paid account, what have you lost?).
So, here is a brief list of things I think need to have password security enforced and those that do not:
Needs Enforced Password Security
Any other form of online financial transactor
ISP logins (especially for dial-up customers)
Paid subscription online games
Pretty much anything else, including, but not limited to:
Free online games
Online communities (
Now, that last one will be controversial, but I just don't think email is that important that I need to keep it under lock and key. Your mileage may vary, but if you use email for the transmission of sensitive info, you have a lot more to think about than simple password security.
EDIT: Thinking about it, there are some pretty good reasons why filesharing communities might want to do everything in their power to stop unauthorised users having access to member's accounts. :)