Bringing affordable housing to the heart of a city can be challenging because that's where development is most coveted and rents — both residential and commercial — tend to rise the quickest and most steeply. It's also usually the densest area and tough to find new places to build.
But putting affordable housing in these areas creates more opportunity for the residents who live in the units. They have better access to transit and to a larger supply of jobs than in farther out areas. With more jobs being in a city center, living nearby means they could end up spending less time and money commuting to work. They also have easier access to food, entertainment and all the other elements a city's downtown offers. [Source]