In my way of putting it, 'ultimate reality' is the reality beyond
existence. But that is a separate discussion. Although I like your take on it.
As to why the evolutionary outlook has taken such a deep hold in our secular-scientific world, I think there are several reasons. One is historical, in that, at the time of Darwin's discoveries, many felt that society needed to evolve from a religious to a scientific view of life. Indeed, many still feel like that, and in some ways it is quite true. That is the outlook known in general terms as 'historical positivism' and it's still a big underlying factor in the discussion.
Another is that humans instinctively seek out myths or stories within which their individual lives are meaningful. Humans are 'meaning-seeking beings'. Hence the evolutionary story situates us in a grand narrative, alongside all the other inhabitants of the natural realm. Apart from explaining 'where we come from' we are then able to say that we evolved to do this or that, or that evolutionary causes account for why we think this or that. So it is virtually assumed - it is simply taken for granted that as we are 'products of evolution' then we should naturally behave in some sense in accordance with evolutionary laws. So this has become, by a kind of sleight-of-hand, a way to replace the traditional notion of 'God's laws' with 'scientific laws' - namely, those 'discovered' by the evolutionary sciences.
The problem is, however, that scientific analysis generally ignores questions of value and meaning. Strictly speaking, it doesn't say anything about such ideas, as it is concerned only with measurable data. In practice, however, this aspect of the scientific method is often combined with positivism, to create an outlook which declares that the world, on the whole, is devoid
of meaning and value, as these things can't be demonstrated 'objectively'. Hence the widespread idea that the universe is intrinsically meaningless. (1) So the problem then becomes that the narrative of evolution, of which we are a part, is basically a mechanical process which has generated human beings quite by chance, as it were - the luck of the draw, just the way things turned out. So even though it offers us an explanation of human nature, it doesn't turn out to be a very satisfying one, from the philosophical viewpoint. We are still felt to be like 'accidental tourists' who just happen to have been churned out by a meaningless material process that has nothing to do with the Universe at large, in which we are tiny, meaningless blips. So it easily gives rise to a nihilist view of life, which I think is extremely common in modern industrial societies (even if many of those who have it don't actually know what it is.)
And I don't know if a lot of the advocates for evolutionary naturalism really grasp that problem.
1. There's a dangerous misconception that lurks in the background of Buddhist discussions of modern cosmology and related ideas. This has to do with the meaning of 'emptiness'. It is easy to imagine that the Buddhist 'emptiness' is related to the discoveries of modern cosmology that the Universe itself comprises astronomically vast expanses of empty space: the 'great void'. There are also comparisons of the higher realities in the Buddhist cosomology as being 'like space'. But this doesn't have anything to do with the real meaning of Śūnyatā, which is, among others, that things are empty because they are not worth clinging to, and they are an illusory source of happiness.
For a sceptical take on the way that Darwinian theory purports to 'explain' the mind, see It Ain't Necessarily So
He that knows it, knows it not.