Of course, the idea of creating a legislative chamber with equal representation from all states regardless of population (to go along with a proportional legislative body) was a central compromise in the writing of the U.S. Constitution. Over at the Washington Post, Ezra Klein suggests that somehow the factors that motivated the Founders into reaching the Great Compromise (or Connecticut Compromise) no longer hold, because the population gap between the smallest and largest states is a lot wider than when the Constitution was written. But his point about the expanding population gap is irrelevant, because the decision to balance the interests of smaller and larger states was more fundamental and philosophical. It was about assuaging concerns that a powerful central government would run roughshod over the states.
It can never be emphasized enough that we live in the United States of America, not simply “America.” That is, we are a collection of distinct entities united together to form a central government to carry out functions that aren’t feasible at the state level. As Federalist No. 62 (believed to have been written by either Alexander Hamilton or James Madison) explains the Senate, “the equal vote allowed to each State is at once a constitutional recognition of the portion of sovereignty remaining in the individual States, and an instrument for preserving that residuary sovereignty. So far the equality ought to be no less acceptable to the large than to the small States; since they are not less solicitous to guard, by every possible expedient, against an improper consolidation of the States into one simple republic.”