Yes, well as I see it, that "most important metaphysical question" is quite the wrong one. But it arises for one reason, and one reason only...ignorance. Let's try some examples of the right question and the wrong question:
Ancient Greek Woman: "our son was struck and killed by lightening today. What caused that, and how can we protect our other children? (Right Question) or "why did Zeus want our son dead and send his lightening? (Wrong Question)" Now, in this example, those ancient Greeks had zero idea of what could cause lightening, and no tools at all to investigate the phenomenon. Now, of course, we know a great deal more, and can answer the "right question" quite easily.
In the seventeenth century, Galileo, through observations of Jupiter using his new telescopes, posited that the Earth revolved around the sun, as Jupiter's satellites orbited Jupiter, along with a study of Copernicus' writings on the Revolutions of the Celestial Orbs. The Inquisition was having none of that, since they asked "how can the Earth move when scripture claims it is fixed and immovable? (Wrong Question) And so, of course, they sentenced Galileo to house arrest for life, and forbade him to teach anything about the matter whatever. This win, by scholasticism and absolutism over reason and humanism also brought the Italian Renaissance to an end. The "right question" would have been something more like "how we can reconcile these observations with what the Bible says?" but, as we know, that is never the sort of question that absolutist believers ever ask. Because they are not seeking knowledge, they are seeking certainty and comfort in their beliefs.
So, the question "does God exist" is a Wrong Question. Many much better questions occur, but you and others like you will never ask them. Things like "why does the world exist," which, after you break that down into the millions of questions that science HAS asked, leads to the answers that tells us what we know now, and will lead us to more answers in future that we don't know now. Asking "does God exist," will never yield anything useful, no matter which answer you choose.