"Looting this item will bind it too you."
You're a person on the go. You can't wait around for loot rolls. You kill the boss and drop the group. So why waste time clicking twice when you could just click once? That's right, if you hit pass, you're done! Since you dropped group the instant you hit greed, you weren't getting the loot anyway.
There is, of course, one downside. If you take the tenth of a second to hit greed before you drop group, you lose out on the 20% chance to screw someone out of a bit of gold for no actual gain to yourself. And that is definitely worth the time for someone like you.
Itemization Changes in 6.2
9 hours ago