Fiber is good for all-around health, whether bulking or cutting. And when cutting, it can lower the glycemic rating of meals and give a greater sense of fullness potentially resulting in less problems with hunger.
But the bad side is that it can interfere with the absorption of nutrients. The solution is to get most of your fiber in meals that are not the ones you get the bulk of your vitamin and mineral supplementation during or your post-workout meal(s).