Repealing the 17th Amendment would strengthen the states’ power against the federal government blob. From el gato malo at boriquagato.com:

the genius of the free market lies in harnessing the power of consumer sovereignty. free people make free choices and these choices provide the information, distilled into simple salients like “demand level” and “price,” that informs every producer in the world what to make and how to make it. this emergent data determines the trade offs faced in production and consumption and perhaps more importantly, it makes these trade offs visible and measurable so that those seeking to serve the market can see and understand what the market’s participants truly want and truly value.
this all stems from those who desire things signaling honestly about their preferences by engaging in trades and behavior. how do i know that you value a snickers bar at more than $1? because you just paid a dollar for it of your own free will. how do i know you valued a candy bar over other possible uses for that dollar? because that’s what you chose to do. economists call this pareto optimality. free people transacting freely only trade something for another thing that they value more and their choices around doing so reveal an honest and irrefutable preference function.
this is a staggering amount of information and it’s what, in a free market, makes the customer king and subjects those who would serve them to the most exacting of discipline. pretty soon, you basically cannot buy a bad dishwasher even if you tried because the rigors of competition and the demands of consumer sovereignty have rendered them extinct. you’re basically guaranteed to get at least 2 of three from the list of “good, fast, cheap” and increasingly, you can often get them all.

but monopoly breaks this. consider cable companies. they were avatars of DMV level awfulness until they started facing competition from other forms of communication and streaming. consider utilities. basically every durable monopoly you run into is underpinned in some way by government. this is because, government itself is a monopoly and as less and less of it becomes even visible, much less accountable to we the people, this only grows worse because government breaks price signals, demand signals, consumer sovereignty, pareto optimality, and most other useful parts of a market.
The year 1913 saw the greatest and “quietest” destruction of the American experiment in governance one might envision
The Federal Reserve was created and the first permanent tax on income was enacted. It was to be the creation of the “greatest” accounting ledger in history. One whose debits and credits enabled the means to finance and PARTIALLY service the resulting unlimited credit made available to the nation’s politicians by the nation’s bankers!
As if to add insult to injury, the 17th Amendment, as “Catitude” so astutely cites, destroyed the Founders vision of “competitive” and “distributed” political power! It could now be “consolidated!”
I believe that because human nature is timeless, repeal of the 17th Amendment would seem to be something that State politicians might find desirable? If enough of them did, it could reignite the Federalism that was key to the American experiment
Reinstituting it with much of the rest of the world remaining the “control group!”