Then I think you're thinking wrong. I really must ask for proof that Linking your FFXI Account to FFXIAH makes you more likely to be hacked. I'm really don't know much about hacking, but to my latest understanding the RMT weren't "Chosing" who they hack. Their hacking involved placing a virus on a computer and using it to get information (for the most part...), When RMT did hacks years back they just virus'd a bunch of FFXI websites and hoped to get hits, they just blindly try to hack people, they can't "Target" individuals, thats now how their program worked.
Unless of course you go around handing out all your computers information/IP Address wherever you go.
The only reason people get hacked is because they don't protect themselves. it has 0 to do with how "known" their character is. Back when RMT were hacking they hacked without caring who they were hacking. They hacked who they could (basically anyone without protection). Of course I won't deny if you piss off the wrong people your account specifically could be targeted, but at the same time, I've only witnessed this a few times, and its always been over something in game.
Players who own a Token, use protective tools like NoScript, Addblock, etc to browse safely on forums will have very very little to worry about, as it will be too much trouble for the average hacker to bother with. with a Token you're really only in danger of a real-time hack, which only happens if you absolutely take no precautions when browsing the internet.
And really, If you don't own a Token and use common internet virus protection programs, you have no right to complain about the "insecurities" these will (not) bring. Because you're not even taking basic steps to protect your account.
I'm sorry but that is the most misused horrible comparison i have ever seen used on a forum. This "Update" is more akin to handing them a Dollar saying "From Dave". Your FFXIAH isn't anything remotely related to the level of personal information as a home address, more like your name, Your first name.
Your Playonline ID would be like giving them your Home Address, and your Password would be the keys to the house.
You're at no greater risk of being hacked from linking your account to here at all. Want to know why? Every time you log in you enter your SE ID/Password, These are linked to your accounts. If they wanted to hack you, guess what? They already have the information they need.