I've been planning on transferring my main to a new account for a while now so I can train up the other two characters on the account without losing any training time on the main. I would have done so already except I always thought charging two plex for the transfer was excessive. I figured it should only be one plex especially since I'll need another (third) plex to activate the new account.
Then I realized why it costs two plex.
The problem is combined with buddy invites, one plex transfers would allow you to get 51 days of playing time per plex. You'd simply start up a new account from a buddy invite to yourself, activate the account with one plex and transfer the character to the new account with a second plex. That's two plex but you'd get one back for activating the trial making the cost one plex for 51 days playing time.
When the 51 days are up you'd just transfer to another new account and leave the old account behind.
Everyone would be doing it. CCPs subscription income per active account would be cut drastically and there'd be millions of unused accounts clogging up their servers.
It all makes sense now. There's a good reason why transfers cost two plex after all.