A benefit of owning property in a local historic district is there are requirements in place that manage change to properties, so that any new or additional development has to fit with the existing neighborhood, according to the adopted design standards. It creates some certainty. There is often a public hearing for proposed changes so the neighborhood can be informed on what is being proposed and can comment on new development.
The responsibility to comply with the design standards and get the required approvals is also applied to the neighborhood, with the expectation that exterior changes, additions and new construction will meet the adopted standards. When you have put a lot of investment into a historic property, this is a way to ensure that investment can be maintained after the property changes owners.