I think the Seventeenth Amendment was long overdue. Who was the audience for the Lincoln-Douglas debates? Legislators? Not hardly. The people were already electing the senators.

In 1789, almost all politics really was local. By 1857, it was national. If the people of a state don't like how their rights have been limited, they can elect reps and senators who will defend those rights. I don't see how anything was lost.

Also consider the advances in communications and transportation between the adoption of the Constitution and the Civil War, not to mention 1912. At the time of the founding, an attention span wasn't all that useful, as information wasn't all that easy to come by. Things change.

I don't think we need a new democracy. We just need to fix the filibuster.