After giving it some thought, I would say that the biggest thing you might lose, on the way to living with less, is a sense of urgency. Or emergency. That is (as the Welder's Wife said), you miss not only the fun of searching for a needle in a clutter haystack or an overstuffed desk drawer, but the embarrassment, panic, and threatened consequences that sometimes go with those searches. We can find more enjoyable ways to get that adrenaline rush.
And it's true, as that post says, that if we suddenly are freed from shopping and maintaining and paying for things, we may have to face questions like "what else is there to do with my time?" As with silence, many of us are a little uncomfortable with empty spaces, both physical and temporal.
But reality sometimes (thankfully) steps in and gives us no choice, or at least makes very clear what choices we need to make, and fast. A Sold sign out front is one way to do it. For some people like Courtney Carver, change comes after a health crisis. Or someone asks us to come on a dragon-hunting adventure, with dwarves...and pack light.