Argentina do the same thing Nico - something about creating Team spirit and pulling together and all that. Personally I'm against it too - David is doing great over in Australia at the moment and I'm happy for him, but in order to play for Argentina in this DC he has sacrificed ALL the Summer tourneys and won't play any ATP tournaments between Wimbledon and Cincinatti
So, in effect, havng struggled back into the Top 10 after Wimby, he will drop straight back out again just because he hasn't participated in any events for 5 weeks.
I have no idea how Nico feels on this issue, but if he is like David then he will give up the points etc without blinking, because Davis Cup seems to be so much more of a big deal in South America than it is in the States or England or many other parts of Europe. Remembering his pride during the Olympics I would imagine that he'll be prepared for the "sacrifice" to help his country just as David is. I personally think it's totally unfair for players to be put in that kind of position out of "patriotism", but I know David is happy to do it and I kind of get the feeling Nico would be too.