Sod the God aspect, what is it with family print Xmas cards?

Last night Guido posted a copy of John Bercow's family christmas card (below) under the title Godless Christmas Card from Bercow.


This prompted a reaction from former Mail on Sunday hack Suzanne Moore on Twitter (now speculating that she was hacked) of the following:

Now, personally I couldn't care less about whether a Christmas card sent by a family has God on it or not. What does worry me is this habit, especially amongst politicians, of sending a Christmas card that has a photo of the whole bloody family on it.

Perhaps I'm alone in thinking it displays a level of narcissism that is creepy. However, what confuses me more is the rationale behind doing it.

Do they think that the people they send Christmas cards to might not know who they are? Or in this case is it more "Look at my posh swanky new grace and favour pad that you're paying for!"?