Thirty-Thousand.org

The Senate was meant to protect states as distinct governments with independent powers. State legislatures are part of those governments. Thus, in pursuing their self-interest, they will tend to seek to protect (even enhance) the political power of the states.
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Importantly, whereas the Founders desired the Senate to be a body more rational, cool, and distant from popular passions, the House’s two-year terms and direct selection by the voters would reflect the people’s more knee-j.erk responses. Of course, gut reactions can prove rash, dangerous, and often damaging to both public good and individual rights. The Senate’s more stoic and thoughtful poise would not result merely from its six-year term but also from the distance state legislative selection created between it and the people. State legislatures would be more likely to pick on the bases of knowledge and virtue rather than mere popularity — hence, the reason the Senate holds special powers the House doesn’t in confirming judicial nominees and ratifying treaties.
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Right now, our country suffers from states overpowered by the national government and a Congress that’s both weak and feckless against bureaucracies, courts, and presidents alike. The 17th Amendment surely isn’t the sole culprit in the development of these woes, but it’s certainly not helping. Its anniversary is no cause for celebration.