Here's the problem with strong passwords: once you have more than a few online accounts, it becomes increasing difficult to remember each account's password. Add to that the annoying security questions a lot of sites ask, and it can be well nigh impossible to remember your passwords unless you (a) write them down, which is very insecure, or (b) use the same password, or a close variant, for all of your accounts, which is also insecure because if one account is hacked, all of your accounts are at risk.