I have mixed views on this. I can see that there could be problems/objections from both sides. IMHO to make playground not only available but also safe, depends on the behaviour of the residents. Perhaps more thought at the planning stage should go into these types of mixed housing.
Near where I live there is newly built social housing on one side of a play area and established privately owned housing on the other side. Since the social housing development the play area has become a no-go for decent people due to intimidation, bad language and needles, condoms, alcohol, cigarette debris, dog dirt and litter. Of course it is not Politically Correct to point the finger at the culprits. Social Inclusion...?