While i agree that it is true that the vast majority of "hacking" cases are from keyloggers, what about the people who haven't played wow for years and come back only to find their account cleaned out?
Having a wow account or a battle.net account these days is certainly not something you do without worrying about potentially losing it, even if you take steps to make sure you system is (reasonably) secure (anti virus, firewall, firefox with noscript/adblock, not going to any obvious trap site linked to from official forums).
Also, I haven't tried it, but i don't think you can login to a game using 1password. Maybe if you copy and paste each time, but that would be a huge pain. I am a huge fan of 1password though and use the random password thing for the vast majority of my website accounts.