In an older neighborhood, everything is already built. You can see what is around the corner, what services are nearby, and who your neighbors are. You can see what kinds of updates are being done by other families to make the most of the space and what kinds of amenities they are adding. Ask your Realtor, or investigate the community on your own. Hot areas net full recovery of remodeling costs.
Improvements help the home, the neighborhood, and the community.
Because of the low margins on new homes, there is very little opportunity for negotiation. The builder is more willing to sit on an unsold home to get the right price because he has more leverage. That can provide needed cash to make repairs without your having to incur a home improvement loan right away. Most existing homes are competing with the clean, fresh look of new homes. Very few will go on the market needing paint and other cosmetic touches.