The previous two Call of Duty games on DS sold 650k and 460k, so it's no wonder that they've released a third.
As for AC, I dunno. The first one seems to have bombed hard on DS, but done pretty well on iPhone. Perhaps the cost of making these games is so low that it doesn't take many unit sales to turn a profit.
Perhaps even when they underperform, publishers punt them out to try to help build franchise recognition. Every copy on a shelf is a little billboard for other games in the franchise. They want people to think, "Oh, Assassin's Creed. I hear the DS game sucks, but I should get around to grabbing it for my 360."
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.
