Then take it further.
Suppose a state wants to coordinate a multi-year state legislative action with a federal one. Or suppose a state wants to align action with other states (e.g., compacts that require Congressional approval). The state would need the Senator to act as an "ambassador" to the federal government, to broker deals with the ambassadors from the other states.
A legislature-appointed Senator would be an extension of the statehouse in Washington, there to bring the needs and desires of the state to the rest of the union of states. This relationship would be much harder to foster, perhaps be impossible, if the Senator were to run a campaign appeal to the people that was disconnected from the interests of the state legislatures.
In fact, today we have Senators who switch parties depending on what "slots" are open to run from, who receive funding from out-of-state groups or other Senators. That kind of Senator has no intention of being an ambassador of the state, but rather, is out for themselves or other non-state interests that they feel more aligned with. At worst, they see the role as merely a stepping-stone to other, grander things.
I think a future essay that explores the concept of Senator as ambassador may be a good one. Just as we have an ambassador to the United Nations to represent our country's interests to the rest of the world, the Senate was to be the forum where the states sent their ambassadors to represent their interests to the United States.
The states cannot do that if the Senate is selected by a method that is in conflict with a state's interests.
-PJ
That is an interesting concept I've never heard before.
I think it would be worthwhile to research:
1) Why the original Constitution had state Senators elected from the legislatures instead of a direct vote of the people. I've always thought it was because the state legislature was a republican-type representation of the people of the state more than a direct vote which is simply a flat democratic majority-rule that can drown out the votes of the smaller communities. I like that idea, of course, but not sure it has made that much of a difference in that aspect of things.
2) What was the reason and intent of the ratifiers of the 17A for going to a direct popular vote.
if the Senator were to run a campaign appeal to the people that was disconnected from the interests of the state legislatures
Seems like you've got a root problem if the wishes of the people of the state are disconnected from their own legislatures.