I'll probably be too busy playing it against random people on the internet to come back to NWR and keep readding more friend codes for the game.
When I get a new game, the LAST thing I want to do is spend time adding friend codes for it. If I could have added those friend codes ahead of time, say, by using the Wii's internal friend code list, then I'd be playing against those people instead.
But the truth is, I'll probably have 5-10 people who want to be on my friend code list who I just won't bother adding because I already have enough opponents.
In terms of economic principles, I'd rather be playing the game than entering friend codes, but I'd enter friend codes if I didn't have the game to play.
There are a whole pile of Wii owners who probably added me to their Wii list (since I'm 2nd or 3rd on the list) who I haven't added because I just don't care to do so, and now even more, since I know that these friend codes are worthless for actual gaming anyway.