Regardless of whether the Wii has actually sold more (total) software at this point in time, it has been on the market for far less time (and probably has lower ownership-months) and is at a point where it is consistently outselling XBox 360 software on a worldwide basis ... This is enough to demonstrate that Wii owners do (in fact) buy software and are not just playing Wii Sports.
The fact of the matter is the comments that "Wii owners don't buy software" and "Third party software doesn't sell well on the Wii" are PR statements that are designed to generate talking points to (hopefully) prevent Nintendo from capatalizing on their lead. Microsoft is fully aware that third party publishers are crunching the numbers and can see that (at the current rate of sales) they will be able to produce a Wii game for 1/4 to 1/2 the price of a HD game and still see potential sales at the same level as a multi-platform HD game (or higher); their goal is to convince publishers that the Wii is not a safe investment, and that they will lose money if they don't develop a game for the XBox 360.
