To develop that big flexor/pronator belly, you need to use wrist flexion. Really heavy wrist curls bother a lot of my lifters' wrists, so we usually go for sets of 8-plus and seek a pump rather than maximal strength.
Wrist rollers are better suited for heavy wrist flexion, and this version is especially challenging since the resistance increases as you roll.
Hey, wanna tick a lot of people off? Want to start a flame war, a heated academic discussion, or just a good old-fashioned penis-waving contest? Then come out publicly and say that total body training is better than body part split training.