The Constitution recognized three entities, the Federal Government, the States, and the People. The function of the Federal government was to be controlled by the States and the People. The House of Representatives was to be the voice of the People, the Senate (chosen by those state governments) was the voice of the States. The intent here was to prevent the States (independently Sovereign) from becoming mere subordinates to the Feds.
To see how this worked out, do you think that the Federal Government would be able to pass ANY "unfunded mandates" upon the States without the 17th Amendment?