In an effort to make form based codes even simpler, how about setting up a series of districts/transects/zones like this:
District 0: Zero buildings per acre
District 1: One building per acre
District 2: Two buildings per acre
District 3: Three buildings per acre
District 4: Four buildings per acre
and so forth. This may seem a bit silly, but it avoids a lot of the complexity involved, while making it very easy for the layperson to understand the zoning map. Each District would also have additional rules:
District 3: 100 feet of frontage, eight parking spaces, 25 foot setback
District 4: 80 feet of frontage, 20 parking spaces, 15 foot setback
District 5: 65 feet frontage, 40 parking spaces, 12 foot build to line, one tree per 30 feet along walking path, FAR's, architectural standards, etc.
The point being that these districts/zones/transects are really easy to understand, and one could set up a small town's zoning around districts that are easier to figure out just by looking at them. With FBC's, one takes a quick look at the town's zoning map, then the chart showing how much density and what building types are permitted, and one knows precisely what one can build.
Good idea? Too simple?