You said a mouthful there. No one wants to walk anymore. It used to be common in our small town to see ladies walking to the local grocery wheeling their little 2-wheel grocery totes. Now everyone wants to drive everywhere; Americans love their cars.
What has happened here in our very rural small town is that the Wal-Mart and Tops were built on the best farmland, and their bulk buying power undercut the local businesses who do not have that advantage. One small example was their horse-equipment department; after the local feed & equipment store went out of business, Wal-Mart dropped that department, so now instead of two choices for buyers there are none. The big store management-level employees were all from out of town, and most of the rest are part-time. While many people love the lower prices and easy parking, their taxes have gone up since Wal-Mart eroded the tax base by putting downtown retailers out of business and by employing out-of-towners.
The presence of Wal-Mart and (foreign owned)Tops is a double-edged sword, and while things are certainly different, I can't honestly say that there is an improved the quality of life or of economics here.
Big box centers are built on "the best farmland" for the same reason that most suburban housing subdivisions and office parks are built on "the best farmland" -- because it's the cheapest land to develop. The land is already cleared and graded.
If you look at old town centers that have been revived pver the last few years, you'll find that they all have one thing in common: they didn't bother trying to compete with retailers like Wal-Mart, Costco, etc. They've basically recognized that the "town center" general retail model doesn't work anymore. Instead, these places are successful because they focus on things where "big box" simply doesn't work. Nobody wants to eat in a restaurant with 3,000 other people, or shop for antiques with 3,000 other Wal-Mart shoppers -- these are the types of businesses that will thrive in an area where pedestrian access is more important than highway access.
I would also add that the typical small-town experience you described is different than what older cities experienced. Wal-Mart may be driving the "Mom & Pop" store out of business in rural areas, but that's because most of rural America seems to have skipped a "generation" in the retail industry. In older urban and suburban areas, these small businesses were already driven to extinction by the post-WW2 generation of regional shopping centers. In most areas of the northeastern U.S., the primary "victims" of Wal-Mart are not small family businesses -- they are Sears, JC Penney, Macy's etc.