It's true that programming FPS controls with the Wiimote+nunchuk is not easy compared to the "old" controls (I mean old by commonly known). Amnd requires a little more teaking. However his statement is a poor excuse, because developers are slowly getting the hang of it and showing how it can be possible.
"A Difficult Platform" is not in terms of development, but in terms of sales. You cannot sell a Core Wii game the way you promote a PS3/360 game. They are very confortable with the HD market (which is not bad by any means). However, blaming sales is an excuse to not admit that they are unable to properly market a Wii core game.
The Wii will have many "trial and error" games and marketign strategy. But gives a great opportunity for other developer to fully try and prove the well stablished games how wrong they can be
