I have a few thoughts on this. I think it is similar to the question "why do we dream?"--what evolutionary survival value is there in that? Well, it appears that sleep is when the brain integrates new information, and processes all kinds of stimuli. Dreams seem to be an epi-phenomena of this processing. It's done for our psychological health. I think that spiritual experiences are analogous; we have them for our psychological health, on a deeper level, one might label it "spiritual health". Bottom line: it keeps us sane.
Yes, I would agree with it, and it's my view that something like meditation should be made something as much a part of public awareness as promoting healthy diet and exercise. It should be including in all school programs like phy ed and healthy lunch programs are. It needs to become a part of our daily lives. It's my view that we are in essence monkeys with oversized brains which makes us particularly anxious and neurotic, especially in a fast-paced, fast changing world. It gets us back in touch with ourselves, reconnects us to the world, and the result is more peaceful, calmer, and happier lives.
Methinks the practices of religion developed the tools to access this. Even if it is not a specific meditation practice as a discipline, the tools of ritual and prayer have the sorts of effects meditation does, and is a form or part of an actual meditation practice. Meditation just goes deeper. We came up with these because it allowed us access to the spiritual side of ourselves we intuitively, existentially, sense disconnection from. That disconnection causes fear and anxiety, and to reconnect with "God", or the world, is to reduce or eliminate that existential fear.
We are wired to the spiritual, to the transcendent, because we became self-aware, consciously thinking about ourselves as individuals in relation to the world. Transcendence beyond that separate self-sense is the only way to relief because we cannot return to nonbeing, to death, to commit suicide. We are trapped between two worlds, as it were, and hence the rise of mythologies of a fall from Paradise to describe this current existential condition. How do we reconnect with that source? We either learn to cope with this dread, or we transcend it. The spiritual experience is geared towards transcending it. We are hardwired to transcend this condition, to grow into being fully self-aware, as opposed to half-awake between heaven and hell in an existential limbo.