It's all us bloody yanks here.
To my knowledge no one from D-Link Europe attends this forum. Which is amusing because our most active user base is international. The higher ups in D-Link EU would presumably be the ones who made the decisions.
For all I know we were afraid that the laws governing aerial placement, specification, and total perceived power output are different and we didn't want to muddle.
Or it could be based on past market trends (perhaps Europe bought less of the last generation aerials).
Or the person who got to make the decisions doesn't like selling aerials because then they would have to support them, and manage another SKU.
This is all just speculation, and that is all your going to get.