Although many might prefer aisle, in our case we have discovered that on the A380 45E and 45F are ideal for us (2 adults + 10 month old very active baby) because we can lay down a blanket and let our daughter crawl around in the spacious leg space without risking being bumped by trolleys, etc and when she is tired, we can have her sleep on us. 45E and 45F have a movable arm rest so we can lift it up and when she sleeps on either of us, we have more space. Also, our daughter tends to start kicking the armrest in her sleep if her legs are resting against it - with the arm rest up, this is no longer a problem. Also, 45E and 45F practically have aisle access because the bulkhead doesn't extend all across the row (since it's the back of the staircase on the A380 which is narrower than the 4 seats). Even with someone sitting in 45D and 45G, you can very easily get out without disturbing them. Also, 45D and 45G always get bumped by people/FAs/trolleys going back and forth.

In the end, we were fine, all went well, not the end of the world, even if our seats weren't changed, I'd be happy to give up my seat for the man and his granddaughter to be together. But my curiousity is more about the protocol (especially since these seats would normally be paid if we didn't have a baby with us which makes me think EK might have accomodated the man and his granddaughter's request since they would have been paying customers whereas we got the seats for free).