Gorath explains it very good. Board games just have a long-standing tradition here.
I'd just add that - this is purely my personal opinion - this has some connections to pen & paper role-playing. Sometimes, there are even products for both sies, especially there are 2 TDE-themed board games out there, and not to forget the classic "RPG lite" board game of Talisman.
Maybe, I just think, if you take the popularity of board games into mind … Could it be that it is easier to understand Germans, then ? And their love for game which involve lots of thinking ?
And apart of it all - it's just fun !
While at school, I organised "board games evenings" for friends once in a month for about a year … It's just fun sitting here and playing them !
And about "Dominion" : It's hugely popular here ! I don't own it, though.
And as a side-note : THe I think biggest bord games fair is still this, where I go to every year for more than 10 years now :
http://www.internationalespieltage.de/e000.php4
There, you can find lots of promo material, can "test" current board games and get them explained ! There you can also get promo material for board games available nohere else !
For Catan, for example I bought a map for the game which has the shape of the U.S.A. … I haven't played it so far, because unfortunately I couldn't build up a group of people willing to play board games with me yet …
Bold printing by me :
Originally Posted by Gorath 
d) Toys are newsworthy. The Spiel des Jahres Award and the opening/closing of the mentioned fares ar prime time news. On a slow day maybe even the top news.
(The situation is nearly inverse for computer and video games. They are still not accepted by the public.)
Very important !
And with that you can understand the German point of view on video games much better !