Power only interest fanboy for bragging.
What's actually matter is the gamed. As long as content is here the console will sale. Look about the releases on the wii and its sales for the last 2 year... No games = no sales.
Also now most of the engines are scalables from smartphones to high end pc so ddifference of power won't be too much as a trouble i think.
"Sales" only interest fanboys for bragging.
Power in graphics are actually something that enhances greatly the quality and experinace in a "Video" Game.
You rather have a movie with cheap special effects, or cutting edge?
Graphics if obviously not the most important aspect in video games, but they are as important as any other.