That's all true to an extent, but it kind of needs emphasis on the first part. 80% of Wii games are shovelware because the Wii is dominating this generation and it's the most likely console for that shit to stick on. Look back at the PS2, the Playstation or the NES. All were the clear dominating console of their generation, in terms of sales, and all had a ratio of about twenty utter shit games to every good to great game.
Where the consumer goes, so too does the shoverlware.
The price point of the Wii plays a large role, too. Now that the 360's arcade bundle is so cheap, don't be surprised if you see a sharp rise in shovelware for it.