It's not just the gluten in grains (sticks to teeth, intestines in many people), grains are also mostly sugar, overstimulate the pancreas, can then lead to metabolic problems, diabetes, heart disease. Other glands can be affected, ie thyroid, adrenals. They can lead to other food intolerances to fruit.
Grains are not always fresh like vegetables are. Some are imported from far away, so not local or easonal.
Grains for me annoying as require too much prep - soaking, washing, cooking, then reacting badly inside, getting in the way of absorbing real nutrients. I don't miss them at all so far and hope I stay focused to avoid them for good. I am enjoying nuts more and love butter, olive oil.
I love veg, a little fruit, fish, red meat, poultry, etc. exercise.