When I saw this suggestion, the first thing I did was checking if it was possible to modify the WP account birthday information. And it seems it can't be done.
So, assuming that they used the WP account information to check if it's your birthday and send a one time non-tradeable item, this might be doable and not-abusable. (If it were tradeable, people would just make new accounts everyday to send gifts to their accounts.
Even so, I don't think they'll put the effort to do it. Not only it might not be as easy as we make it sound, but it's also something that will happen once every year for each player. So players won't be aware of it until it's their birthday or someone tells them, and even then they'll probably forget by then. So there's no guarantee people will login to play on that day.
As a pro there's the fact that it's a nice gesture. But that alone will probably not be enough to justify the development time required for it.
Edit: Not to mention almost any item in the game can be obtained in one way or another (like the vips in attendance). There's hardly anything we'd consider "worth" as a birthday gift.
Edited by faku1810, 02 July 2015 - 06:54 PM.