A somewhat useful summary comes from the penultimate page:
"Neither niche theory nor neutral theory provides a satisfying narrative for ecological communities, and the defense of one or the other (sometimes both) by ecologists has at times slowed progress toward understanding biodiversity."
Earlier in the paper, he argues pretty emphatically that neutral theory is a waste of ecologists' time, because there are examples of it not explaining observed patterns, and because some of its assumptions and/or predictions are not realistic, even in principle. He also argues that niche theory (as typified by Lotka, Hutchinson, MacArthur, Lack, Elton, Gause, and others) is highly limited in its usefulness.
I would say the same thing about natural history, that natural history alone does not provide a satisfying narrative for ecological communities, because, unfortunately, words can sometimes be horribly ambiguous and non-quantitative. I would also argue that we need mathematics because it is the least ambiguous language we have, and that its quantitative nature underlies the nature Ricklefs wants us to spend more time observing.
I heartily agree with his sentiment that we need to spend more time observing nature. The scientific culture needs to find ways to reward useful, organized, and detailed observation of natural history. However, I don't think we should throw the baby out with the bath water.
Josh Tewksbury is one of many examples of an ecologists that seems to have equal respect for, and grasp of, both natural history and theory. Long ago, I had the pleasure of listening to a talk of his at Miami University, in which introduced his thinking about ecology as the combination or unity of natural history, theory, and experiment. He was a bit more dogmatic about it, or perhaps just enthusiastic. Regardless, it struck a positive chord with me, because I think his goal is the goal of all ecology and evolutionary biology. I guess I think not everyone needs to do it all, nor all at once.