Many strong arguments can be made for not standardizing. Nature has produced a pharmacy of chemicals in each plant. Man has learned to use the whole plant largely by experience in the treatment of various conditions. To standardize is to change this equation and nullify the experience. At the current price of commercial herbal-alternatives to pharmaceutical compounds, why not get the dried plant and make your own herbal medicines.
Many good books exist on how to do it at a fraction of the cost of the bought variety.