Mattes said that the system just couldn't handle what his team wanted to achieve, saying "the AI of Elika was highly advanced and required a lot of processing power; the world size and dynamic loading, the draw distance, the number of polygons in the characters... If we had done a Wii version, it would have been toned down, probably linear, it wouldn't have been an open-world game, and so it would have been a very different experience. We didn't want to water it down that way."
... Plus, they couldn't have charged Wii owners $10 for the "Epilogue" DLC! No, no, we kid.