The DS is pretty much a cash cow to Ubi. Most of their games for it seem to have low cost production aimed at young girls and are churned out at a high volume with a regular price tag.
Quantity is more important than Quality, and that's clear from the number of games that Ubi release which are inconsistent when it comes to game play. Not all there games are dire, but it seems very hit or miss which games have potential and which games are clearly rushed out without any real thought.