I doubt grains are that big a deal for most people.
Unsaturated fats are the only thing in the diet that is clearly bad and people still eat loads.
C.f. http://www.scientificamerican.com/article.cfm?id=carbs-again... "In March the American Journal of Clinical Nutrition published a meta-analysis—which combines data from several studies—that compared the reported daily food intake of nearly 350,000 people against their risk of developing cardiovascular disease over a period of five to 23 years. The analysis, overseen by Ronald M. Krauss, director of atherosclerosis research at the Children’s Hospital Oakland Research Institute, found no association between the amount of saturated fat consumed and the risk of heart disease."
Coconut oil and dairy fat are safe. Other fats should really be minimized. To the extent that any fatty acids are "essential" you'll easily get them incidentally from foods. All vegetable oils are bad for you and fish oils are bad for you.
That being said, from what I can tell, unsaturated fats are a far cry from your claim of "clearly bad", and even farther from "the only thing in a diet that's clearly bad". From a quick Google search, it appears that there's preliminary evidence that high amounts of PUFAs increase the rate of metastasis in rats with cancer, and preliminary evidence that high amounts of PUFAs decreases the "all-cause mortality" rate and rate of cancer events in humans with cancer. With such a low bar for "clearly bad", one could dig up a thousand and one studies about refined carbs (let alone sugar) that make it infinitely more "clearly bad".
*I mean that in the sense of reading up on things from reliable sources (studies etc), not that I'm a researcher