You know that "Compact Gears" doesn't refer to the fact that there are only two chainrings? It refers to the fact that the two chainrings are smaller. 50/34 is pretty typical for a compact whereas 53/39 is pretty normal for a standard double crank set.

The *compact* double is geared lower and is a compromise between top speed and hill climbing ability while maintaining only two chain rings. Really, I think they are aimed at the amateur rider who can't push big gears from a standard up a hill.