why the shoe repair shop makes me happy (or: what's not to like about mixed use neighbourhoods?)

Often, when I walk past the shoe repair shop, it strikes me just how fantastic my neighbourhood is. Really, it's the prototypical mixed use neighbourhood. Within a three block radius of home, I have access to a grocery store, two hair dressers, a video store, several pubs, at least six different restaurants, a newsagent, a museum, two parks a metro station, the highway, if I happened to want it, and of course, the previously mentioned shoe repair shop. All of that, on top of the whole pile of mixed residential, as well as the office buildings two streets over.

I don't ever need to leave the bubble. And that's what makes me wonder. I have trouble grasping why anyone would want to live in an area that didn't have everything within reach. Is it actually pleasant to have to leave the neighbourhood to get groceries? Is there some factor in non-mixed neighbourhoods that makes it worth the inconvenience? I find it very hard to believe that anyone would be willing to trade the corner store for a detached house and a yard.

My neighbourhood forces me to exercise, because most things that I need or want are within walking distance. Because I can walk, I don't need to spend money on maintaining and fuelling a car. The sheer proximity of amenities gives me the opportunity to be healthier and have more disposable income. What's not to like about that situation?