Ian, gotta disagree with you about having Polarium as a pack-in. Nintendo would probably want to showcase the graphical prowess of the DS just a little bit more than what Polarium shows. In addition, i think that Polarium is kind of a niche game whereas the vast majority of everyone loves Mario. People will say, "woopy do, the DS comes with some weird crappy looking puzzle game I've never heard of" versus "Wow, Mario comes with the DS now, I loved that game for N64 and wait, it has MORE stars AND mini-games AND wireless multi-player? Wow, the DS is great!"
Okay, so maybe a little far-fetched, but I think you get the idea. Mario sells systems. Polarium doesn't.
-Blueflame
(Btw, I own and enjoy both Mario 64 DS and Polarium)