it's quite the opposite: a nicely designed park/other place is more secure due to 'public control' (it's harder to do illegal stuff where there are many people watching and are against this). If public space is poorly designed, it'll be uncomfortable for kids/parents/teenagers and will attract marginalized people, like a space that looks shady, hard to reach and has design for gathering of drinking people

Also it depends of city strategy> having marginalized only buildings/areas is a bad idea, that's why in states like baltics, social apartments(the new ones) are not separate full buildings, but just apartments spread evenly across the city, contributing to diluting concentration of marginalized people in one spot and 'social control' keeps these regions safe