There are many functions of government that have to do with things other than the protection of individual rights. I would like more information on where this concept comes from. One sentence, out of context, from the Declaration of Independance does not cut it.
Conjures up images of abuse of power, doesn't it? Given that I'm no expert, I'll respond to what I can.
Establishment of Memorial Day? Government has the power to raise and army and navy to protect our rights to life, liberty, and property. Memorial Day can be a way to express our gratitude to those who served, thereby encouraging future citizens to choose such service in protection of our rights.
Postal System? Probably an internal mechanism of government as it exercised its just powers. Elements of government must communicate among themselves and with the citizenry.
Scientific Research? Depends on the project. Some might be justified under research for military purposes. Protection of property rights could be cited for things like pesticides. Protection of life for medical research.
Interstate Highway? Was justified by Eisenhower for efficient military movement and civilian evacuation should we be attacked.