We are their employers and we have the right to know what they are doing.
How long would a person stay employed if he insisted on keeping what he does at work, a secret from his boss?
The state legislature, should be the Senate's employer though, not the mob. The people are the employers of the House, and the state legislatures who chooses Senators. This is the original system before the XVII amendment, and its better for checks and balances. It is also easier for a state legislature to keep tabs on their Senator and kick them out if they aren't representing the state properly.