Good point... rebuilding from ashes typically does NOT end up in more liberty. The american experiment was something different than the world has really ever seen, and did NOT work in the second revolution(aka civil war 1). The civil war resulted in a hugely strengthened central government as these united states transformed into THE united states.
Typically power vacuums are filled by warlords and tyrants. Thinking that scrapping our current govt and replacing it will increase liberty(especially when we are THE global superpower) does not fully take this in to account.