I don't consider the brown component of rice to be an asset. Nor do I consider the skins of potato to be. They both contain irritants to prevent animals from eating them, and psyllium fiber in grains in my opinion is an anti-nutrient that harms intestinal bacteria and the gut lining.
If you want fiber, pectin, cellulose and resistant potato starch are the best for gut health and flora. Psyllium rips up intestinal cells. That is a fact. Some nutritionists think it is a good thing to occasionally rip up intestinal cells, but no one denies that psyllium does so.