When we have a government without corruption, we probably won't need to be armed. That isn't the case today. Checks and balances work in a young government, but after hundreds of years, friendships, camaraderies, it's not difficult to have loosely coupled groups infiltrating all branches. Things eventually crumble as perfect systems are hard.

This is akin to the monarchies, where a king may have risen to power as a good leader, but a later king may not have been so kind.

These things aren't perfect, but having multiple systems to pick up where other systems fail provides us the ultimate leverage in the end.

Would you take airbags out of cars because they sometimes fail and always harm those who feel their impact and chemicals and everyone is "supposed to wear seat belts by law" anyway?