Depends on the character. Ryu can get a PL- Shoho izuna for little exceution, and it does more than a PB even with a wall.
Think about it this way... your near a wall (Wrestling Stage) and you PB... your not gonna be able to follow up. With a PL, you can launch, get most likely the same damage but even more due to the bounce off of the wall and the huge juggle combo.