Because a company can charge as much as they want to. SNES and Sega games were upto $90USD when they came out, even when the standard price was $50-$60. Nintendo is trying to entice developers by offering a high price point to consumers that is still below PS3/360 prices. Of course, however, it also means that multi-ports for PS3/360 will make more revenue (but not neccessarily profits)
Back from the dead, I'm afraid.







