Starchy carbs (white or brown rice, potatoes, etc.) in general have a lower nutrient density (nutrients-to-calorie ratio) than other veggies, especially green leafies (which are the most nutrient dense). They pack less of a nutritional punch than some other foods in terms of vitamins and minerals, with more calories. (whole grains are starchy as well, but they contain the germ and bran of the grain, which gives them a bit more nutrition. There are numerous books out...like "Grain Damage"...that discuss the negatives to grains, which are usually acid forming.)
They vary in nutrition. For example, yams have lots of vitamin A and are healthier than white potatoes.
They also have other characteristics that make them less desireable than other foods:
Some (like carrots and beets) have been hybridized to the point of being very high in sugar, and are best mixed with lower-sugar-content foods.
Others (like corn and wheat) are so prevalent in the standard American diet that people can develop sensitivities to them. Also, most corn that is not organic is genetically engineered. Wheat is a very acidic food.