An exclusive event would make sense. You have the time and space to really have focus lent to your games, without having to fight for attention and space in E3. To us it may sound odd that something as prolific in name as FFXV would need to fight for attention, because we're fans of the franchise and we've been keeping close tabs on the game for a long while, but across the general picture, FFXV is just one game among others, not really primus inter pares. Plus of course, you won't have to dedicate attention to the Eidos side.