There are the issues of utilizing engines and whatnot, the idea that you can make a long-term investment in HD Development by maintaining an engine and thus bringing costs down for successive games. But these are alternatives that can only really be applied by the biggest and the best 3rd parties effectively, and therein lies the problem
Wii games fetch more profit, if less revenue, so it depends on how it incorporates into your strategy. But as a rule of thumb, it is just cheaper.
Monster Hunter: pissing me off since 2010.