You can also host such debates with the 17th Amendment repealed. The candidates can make their case in front of the legislators, and the voters can watch and petition their legislators to vote according to their will, depending on what they find out. (Prior to the 17th Amendment, the political party duopoly had an iron grip on the legislatures.)
If you can convince people to surrender their right to vote for senators, more power to you!
But I don’t have much confidence in such an idea getting popular. So we need workarounds at the same time.