The criticism of the property developer seems pretty justified to me. If you don't mix up various classes in one zone you get slum areas like the Parisian suburbs - only good for rioting. Sadly when you put the poor where the rest of society can't see them, little tends to be done to resolve their problems. Also the further out the poor go, the harder it is for them to find work, owing to transport costs. That's why any new housing built in London, for example, has to include a certain amount of "social housing" (i.e. low cost). Governments tend to get around to this eventually, but by the time they realise no police/teachers/plumbers can afford to live in the centre of town it takes a mammoth effort to resolve.