You miss the point. Senators are supposed to be representatives of the state legislatures. Representatives are representatives of the people. When both of them are elected by the people, we have pure democracy. Pure democracy always devolves to the masses voting themselves funds from the public treasury.
It makes sense but you’re going to play hell convincing people to give up their “right” to vote for senators. Pete Hoekstra was no conservative firebrand but he made an offhand comment about needing to fix the 17th Amendment and was met with immediate sustained screeching about wanting to strip people of the right to vote.
As far as the legislatures electing senators, obviously it would be better as far as the GOP is concerned but I’m not very trusting of the state legislatures either. On the other hand, it might just get people more involved in legislative politics which would be a good thing.
I’m still thinking my way through this but I can’t ignore the fact that it would be an awfully hard sell with the people.