I don’t disagree with you, but I think the human mind is essentially programmed to seek first causes. Part of what has made us so successful as a species is that we want to chase patterns down to their foundations, and I think it’s natural to feel that there is some “root” truth that explains the entirety of existence. I think that’s why a lot of people turn to simplistic unifying philosophies; it reduces a lot of intellectual anxiety if you have one big idea that subsumes all others, and upon which you can fall back when faced with uncomfortable questions. All of which is a long way of saying that while you’re correct, I think as a species we’ll always trend towards trying to find “THE foundation” even when the more rational thing is to “pick and choose” like you’re suggesting.