You can play quickly and directly. Ideally, you play close to the table with pips.
Each stroke has a fixed amount of energy -- some percentage of your energy goes into spin, and the rest goes into (linear) speed. With pips, you're not generating much spin, so nearly 100% of your energy goes into speed.
The backhand side is more natural for a quick, punching/flicking stroke (with the handshake grip, at least) and this is why most pips players tend to use it on the backhand.
However, there are some reasons to use pips on the forehand:
1. Penholders playing with the traditional Chinese style (for example, Liu Guoliang). This style involves a lot of (chop)blocking and punching close to the table.
2. Players whose forehand stroke is too slow. This happens for taller players with longer arms (for example, Mattias Falck) who seem not to be able to do topspin strokes very quickly. Playing pips on the forehand allows them to play a shorter stroke.
