Very good post, I agree with the majority of what you are writing. I will look into the paleo diet helping cure various ailments, but there are all kinds of diet studies that show cures for ailments, such as high-carb low fat removing ailments, that doesn't prove anything to me. There was a recent long-term diet study showing that middle aged-people that ate a diet that was higher than 20% protein had twice the risk of dying of heart attack or stroke and also increased risk of dying of cancer and other diseases, compared to those that ate less than 20% of their calories from protein. The same study showed that the elderly over the ages of 60 or so actually benefited from diets with more than 20% protein. What does this study prove? Well really nothing, it is all about the interpretation. Why did these results occur? I have some ideas, could it be in elderly people proteins are more rapidly depleted from the body, so the extra protein was a benefit? Could it be that the middle-aged people who perhaps didn't need the excess protein were causing a burden to their bodies with the excess protein? Well, this idea would also fit in with your intensely active cross-trainers, wouldn't they also need a larger amount of protein in their diet to replenish their bodies from the intensive training? This is how my mind works, I try to make sense of why people may feel good on a certain type of diet while another may find harm from the same diet.
I have think about the same things you wrote about in your post and they are all very good points. Yes probably a lot the fruits that we eat today are a bit sugar-heavy, but I have eaten heritage apple varieties that are hundreds of years old that were native to Northeastern Pennsylvania and they do have much more complex flavors than many of the apples we eat today, but overall it just tastes like an apple, it is still sweet. Look at figs and dates, they have been growing for 1000s of years in exactly the form that we know them today and they are filled with Sugar and also tons of minerals and nutrients. Fruits are one of the best (if not the absolute best) source of minerals, the trees go deep into the earth and get all of those minerals out of the ground. Fruit is one of the most nourishing foods, not just to our body but also to our mind. On a deeper level (I know not scientific at all), look at how amazing a fruit tree is. It grows for years and years, giving the fruit that can nourish all sorts of animals without hurting the tree itself in any way. I know I sound like a fruitarian here, which I most certainly am not, but really fruit is one of the most amazing foods and a miracle of nature, and anyone who avoids this food that God put on this earth (yes I went there), for the nourishment of our bodies and minds, that is just a shame.