When you develop to the minimum legal guidelines, then you will see more house and less yard. This new neighborhood is being developed from the ground up to the minimum setbacks. It will have more conformity than some of the surrounding streets because of this visual consistency.
At R-10 or R-6, the minimum side setback is 5 feet, but the combined left and right must be 15 feet. So one house may be 5 feet from the line on one side and 10 feet from the other side. Houses in this zoning will generally have a driveway on the wide side, and no drive on the short side. This means that the minimum spacing between houses could be 10 feet and the the maximum could be 20 feet.
This is what 15 feet looks like:
This is what 10 feet looks like:
When homes are torn down and replaced with structures that conform to the letter of the law, they may not blend with the spirit of the established community.