I know this must hurt the head of those who truly hate Electronic Arts. But in all fairness, the game is a break from their image as a company that buys up smaller developers and churn out nearly identical sequels until people get fed up, then close the shop and buy another. The Sims 3 is the first in the series to be made by EA rather than Maxis, but it has a lot of improvements, including - incredibly enough - running better than the 2004 predecessor on most modern computers. This is achieved by using dual and multi-core processors as well as offering a wide range of graphic detail levels. Creativity and technical excellence in one and the same game, not something we had expected from EA.
The large legitimate sale is probably in no small part due to the game's popularity among women, who are generally less eager to commit crimes and risk going toe to toe with computer viruses. (There are certainly exceptions to this, but this type is fairly common in the player base.) The game is also available for the Mac from day 1.