Nutritional Science keeps finding out new effects and necessities, where micronutrients are concerned. Unless you're satisfied at the state of nutritional science, you should feel no safer eating foods genetically modified to remove unknown impurities and replace them with known vitamins than you would eating an isocaloric mixture of ghee, bleached flour, egg white, and a multivitamin supplement.

edit: It seems I was unclear. What I'm saying is that, in addition to the 13 essential vitamins identified by the NIH, normal food contains thousands upon thousands of chemical compounds with as-yet unknown effects and threshhold doses. Moreover, it is unlikely that a gene insertion or deletion intended only to increase round-up resistance has no effect on its physical makeup.

Thus, a belief that the only nutrition which contributes to health is the 13 essential vitamins, plus a good macronutrient ratio, is equivalent to the belief that the only reason to eat more than pure fat, carbohydrate, and protein plus a multivitamin is a taste for variety.