Although I'm not happy with the number of ports on the Wii but I can't blame publishers for doing it either ...
The main reasons PS3 and XBox 360 games have such higher development costs is they require far more developers, working for a much longer timeframe, in order to produce a game; it is not uncommon for PS3 or XBox 360 games to take 2 to 3 years to develop with a development team that is twice the size of a PS2 project.
Publishers heavily banked on the success of the PS3 from the start and many of the best development teams were allocated to produce PS3 games before it launched (and possibly before the price was announced at E3 2006); many of these projects have still not been released so the development team is still not available to work on anything except for that project.
Now the sales of the Wii means that third party publishers want to heavily support the Wii, and they really want their high quality well known franchises released on the system; at the same time their (from the ground up) bigger budget, high quality Wii games may be 9 (or more) months away, they have very limited resources to allocate to more Wii games, and they need more Wii games today. The result of all of these factors is driving publishers to take previously completed games and invest in some rework for the Wii.
