[kahljorn]

its the only way to give each of the states a somewhat equal say in the government, which pretty much all goes back to white slave owners being outpopulated by white northerners. Theoretically you could also argue it's because people are stupid, you don't want them controlling everything, and so they need a check and balance too.

also with that whole experiment of the states thing where each states can have its own laws more or less. If each state didn't have that level of representation, then its state-wide laws could too easily be negated at a federal level.
For example, everybody could vote against abortion and it would be illegal everywhere.