But people need to keep in mind the complexities of keeping one SKU. The Wii had a low price point from the begining so they didn't need to take microsofts/sony's routue of making a cheaper SKU to apeal to casual/poorer gamers.
To an extent you have no control over how many SKU's you want to release unless you don't care about being profitable , Sony hasn't been as popular as they hoped so a multiple SKU was neccasery to reduce their losses.
A multiple SKU strategy is more of a reaction to changes in the market more than anything.