I've only ever needed one account on one Square Enix website to play this game... Maybe I'm missing something, but I've never had any trouble since they introduced the Square Enix Account Management System. Isn't there only two separate account management sites? One is for FFXI and FFXIV services, the other is to just buy from their online store and register games you've bought.

However, if they can just combine all of that into one easy-to-access account management system (I'm assuming this is what Mog Net will be?) similar to Battle.net or Steam, then I'm all for it!

P.S. Not sure why people had trouble, but Square just emailed me the PSN pre-order code to input into my PS3 and I had no issues at all.