AREA 17 makes it pretty clear why. This article is packed with tips and screenshots that will make sure you are pixel perfect. Fireworks was as good maybe even better until it became unsupported. That’s right I said it, Fireworks.
The Pixel School is a design methodology created by Arnaud Mercier (May 10, 1972 – September 26, 2011) and formalized by AREA 17. It is a defined way of working that has great impact on the final product. It consists of a set of design principles and the techniques to achieve them.