The benefit would come years down the road. Much of the money pressure, need to campaign, and the like would be gone or minimized, and after a while the makeup of the senate would be quite different.
And I think it would be easier to change out a senator, if a small number of state politicians were in charge of his job.
It took a few years for the senate to become what it is, I think it would take longer to get it back.
I’ve reviewed it from every which way (indeed, I’ve researched every person to have ever held a seat in Congress), and what you think will happen (in a positive way with a better class of Senators and perhaps state legislators) simply won’t. I suggest taking a look what happened during the last decades from the 19th century through to the ratification of the 17th. There’s a reason why it was passed. Big money, special interests, personal fiefdoms, hackery and the like... it was all there, and many of them were not “high minded” of the Constitution and states rights. With the people having a direct say, it levelled the playing field a bit. It’s better how it is now.