I don't think anyone ever doubted that Nintendo published 1st party games were doing badly on the Wii, be it hardcore or casual titles. They did great and better than they ever did before.
The real issue comes in when you compare the overall 1st+3rd party software of the Wii with that of PS3 or 360 that are core titles. If you put up that list of 30 1st party games along with whatever core 3rd party titles that the Wii has beside those offered on the 360 or PS3, then you really start to see the difference. When the PS3/360 were getting several core titles every month, Wii was only getting a few big Nintendo releases a year. That is where this whole, Wii abandoned core thing comes from even though it isn't strictly true from a 1st party perspective. But you can't ignore 3rd party.
