When it comes to loss of community, that probably deserves it's own thread. But I will say our modern way of building neighborhoods isn't doing any favors. America sucks at building public spaces. Our housing developments are sprawling spaghetti webs of roads. People get in their cars, drive to the massive shopping center on a six lane road, and then go home in their car. There is little to no chance of spontaneous social interaction in that process. People don't go outside much because we don't give them a reason to. We need more parks, more squares, more gathering points where people just go and hangout. Instead, we get industrial scale development that has about as much character as a gray cube, made to maximize profit. Europe will always blow America away in public spaces because it was mainly built before cars.
Things need to be built on a human scale to encourage community, not a car scale. This doesn't go for every area in the US (i.e. older areas, Seaside & Celebration, FL), but by and large it is the dominant pattern of development the last 30 years. The amount of land and resources we are using to create these developments is mind-blowing.
I could go on an epic rant about how suburban life is not conducive to a person's(and therefore society's) well-being but I'll save that for another time.
The thing about the over-reliance on cars, is that roads act like barriers as much as they do as thoroughfares. A major urban road serves like a "Berlin Wall" dividing communities, especially if it's one of those elevated 'urban motorways'. It also blights everything around it, with noise, pollution, and loss of sunlight.
I grew up partly among the remnants of Luffwaffe bombing in WW2 (all those still-undeveloped bomb sites, plus people still living in the prefab 'temporary' housing that was put up quickly after the war to cope with the loss of homes to the Blitz) and partly among the damage done by the aborted post-war "London ringways project" that was supposed to build mulitple concentric rings of urban motorways through they city. The latter would have been much more devestating than the former had they not cancalled the project early on. Even cancelled as it was you could still see evidence of the damage done by the initial stages of it - only quite recently did I hear about that project and realise why those bits of the city were so blighted in my childhood)
I guess in the US, with it's extreme love-affair with the car, "suburbs" are very clearly defined things, but here I'm not entirely sure what a suburb even is. I've seem the same areas called a 'suburb' or 'inner city' by different sources. Across the Channel in Paris, of course, the suburbs are where the poorer and non-white people live, which seems like the reverse of the US.
The one positive that can be said for "suburbia" is that, apparently, studies find you get the highest level of biodiversity in those areas - higher than in the inner city and also higher than our artificial, remoulded and pesticide-treated "countryside". It seems like the last refuge of the bees and the foxes.