It isn't fair, because cities evolve to fit the types of transportation available. But putting fairness aside, which one is better? I've been to Florence and I've been to Atlanta... And once you've come to the conclusion that, well, maybe you'd really prefer to live/work/vacation in a city "designed" like Florence rather than one engineered like Atlanta, I think it's time to figure out how to make the latter more like the former. Desuburbanization is a bit of a trend. I don't know how practical. But I can hope. As far as looking at old/new world city planning, your image works way better.
Florence might be the better urban form. The question is not just which one is better, but also for whom it is better. For a social twenty something urban dweller it probably is, but for the average household family? I doubt it. While I detest the single-zone suburban form because of the (negative) effects it has on the city and its society, its demand is undeniable. Most families will want their private, spacious property. Getting rid of suburbia will not rid us of that demand. Rather, I think there's a lot to be gained by scaling down suburbia to reasonable property sizes. Reduce the footprint of properties and focus more on walkable medium density mixed-use developments for families. Expecting the general population to somehow go from suburbia to something remotely like Florence is unreasonable, I think. Even in the lively and dense urban core that I live in there's hardly any families living here. Different people have different needs, and it is those needs that are used to to change the urban form.
I don't think the demand for suburbia is still so strong, but then I've never had a family. Personally I'd rather my children grew up in a center of culture, learning their way around a city, becoming independent, than in sheltered, dull suburbia. Neighborhood park substitutes for front yard, hopefully crime isn't a factor. American suburbia exploded postwar, and the needs of the populace now are different than they were then -- but we're locked in, because of shortterm profit-maximizing infrastructure decisions. I think if we could get a fresh start, maybe the preference for space over community might fade. Mixed-use hybridized communities are a more practical step -- you might check out that thing I just posted about an Austin neighborhood that got featured on NPR's Cities Project. It's half and half.