Re: Power unchecked
The USA is not a unitary democracy, but a federation of states. Each state is a democracy, majority rule. If the majority in many states is by a (fairly common) not-overwhelming margin...but there is one large extremely populous state that has formed something like a Uniparty (generally through very high spending and government-employee unions, i.e. California), then the electoral vote winner may well not be the "popular vote winner." We have, though, no such thing as a "national popular vote winner," because we've intentionally never subjected ourselves, and our states, to such.
The electoral college system actually provides a damping system in case one very populous state has very non-diverse politics. Without it national institutions and laws would quickly come to reflect only that state's Uniparty beliefs and policies.