The pros of sidewalks generally dominate the cons.
1) Sidewalks can enhance safety. Pedestrian safety, especially for children walking to school, is vital. Increasing sidewalk networks in areas where people live, learn, work, and play helps keep children and families safe.
2) Sidewalks can help reduce vehicle emissions by promoting a substitute for driving and helping residents save some money on gas.
3) Neighborhoods with sidewalks may have higher housing values. An Urban Land Institute study indicated that homebuyers are willing to pay a $20,000 premium for homes in pedestrian-friendly communities.
4) Properly maintained sidewalks are potentially attractive features that provide separation between private property and roads and aid in erosion control.
1) Sidewalks require significant expenses associated with construction (especially retrofits).
2) Sidewalks require significant maintenance.
3) Sidewalks may induce litigation related to poor mainteance, uneven surfaces, lack of ADA compliance, etc.
In most communities and neighborhoods, sidewalks should be preferred.
Some communities prefer not to have sidewalks, though. Instead, these communities may prefer to have, for instance, bike and horse trails. Such preferences may be a function of the average distance between homes, the local topography, the neighborhood layout, or other factors.
"Safe Routes to Schools" programs under the Safe Schools Initiatives programs don't necessarily mandate sidewalks, but there need to be compelling reasons.