The basic idea is that the will of the people may change at a whim, and that we therefore need safeguards to protect liberal parlamentarism and the basic order of society from changes that would otherwise be disruptive. This obviously protects the so-called elites from angry mobs, which is the main argument against this system, but it also make sure that our economies don't collapse due to various governments doing things like forced take-overs of international banks in times of financial unrest.

Alas, this order is often defended in the name of "democracy" when it's outright anti-democratic and patronizing.