Wheat and wheat bran is among the most available, easily digested forms of food available.
Wheat contains significant amounts of protein (when whole) as well as sugars all of which contribute to the formation of blood components and energy stores.
The nutrients both macro and micro are easily broken down and accessed by the body.
It is a simple, cheap food which has significant nutritional value.
You are made to believe that it is unhealthy because then you will look to more expensive and less nutrient dense options which require far more difficult farming techniques. Wheat as a wholegrain is a whole food that could easily solve the hunger problems of third world countries.
Gluten is a protein. It is not an inherently unhealthy thing. What is unhealthy is the amount of weight people place on gluten as contributing to their health problems. They do this from a lack of knowledge and simply by accepting the ludicrous claims that have been made about gluten causing 'leaky gut' or massive autoimmune reactions on a widespread scale when in fact these conditions are extremely rare and the reactions of its sufferers often require hospitalization as they are life threatening.
This is due to mis appropriation and disturbed function of the immune system, not because of gluten.
Many people who complain they are gluten intolerant because they get some bloating after eating bread neglect to mention the alcohol they drink every weekend, or the antidepressants they take daily, or the fact that they eat raw, uncooked cold food nearly every other day all of which out huge strain on and disrupt the normal digestive functioning. Then they have one piece of bread and a bit of bloating, flatus or diarrhea and it's gluten intolerance.
Then of course if that one person can't have it then it must be an unhealthy food unfit for human consumption. The way the trend is going towards labeling foods as unhealthy, (including water) we won't be eating or drinking anything that doesn't cost $3,000 a gram from all the organic certification and lab testing it has been through to make sure it doesn't have the slightest impurity or toxic substance in it.
Then when our bodies come into contact with those substances later down the track as we invariably will, we will shrivel and die because the body won't be able to cope assuming the system has never been exposed to them.
Obviously this is a bit extreme but I hope you get what I am saying...
Your attitude towards food and how you manage your healthy eating is half the battle to having it well digested and nourishing as your qi and your mind nourish the food you eat with energy. Bad energy equals a bad outcome regardless of the quality or lack thereof of the food.