IMO your examples don’t really prove your point.
1. Bruce - I doubt seriously if would have mattered if he had followed the legislators instructions down to the capital or noncapital letter, comma, period and semicolon. He was viewed by the legislature as a black carpetbagger and that was that ! He had to go ! The issue was race & revenge not politics.
2. Ross - Was the state legisture asked its opinion? Is there a record of their instructions directing his vote? If not this is what you surmise to be the case. It may be or not be. Ross lost his bid for re-election two years later. If his Johnson impeachment vote was the issue his re-election hung on he paid a price for his action. The legislature refused to send him back as was their Constitutional right. In the mind of the state legislature he was acting against the interests of the state.
3. Benton - He opposed the Compromise of 1850 as too favorable to pro-slavery interests. This stance damaged Benton’s popularity in Missouri, and the state legislature denied him re-election in 1851. Again a senator paid an electoral price for antagonizing the state legislature. Again in the mind of the state legislature he was acting against the interests of the state.
To me in 2 of your 3 examples the old system clearly worked ! The legislative-picked senators served their Constitutional term but in that term ran afoul of their state legislatures wishes and were negatively rewarded for it.
So you don’t subscribe to Edmund Burke’s maxim that a legislator shouldn’t just parrot his constitients views and demands but one who exercises his judgement. If his constitients find his judgement wrong then they can replace him. In cases 2 & 3 they did ! The first one Bruce is simply a pathological case and proves little.
I disagree, and while you may explain away the three examples, it’s still ultimately a rationalization and my central point still remains here.
The point, of course, being that by the strict standards, they’re supposed to follow the legislature’s instructions given to them on how to vote. This is the entire point of having the legislature vote on their Senators. Once that’s been breached, with respect to the aforementioned 3 examples, you have a Senator who is disregarding, indeed betraying, the explicit intent/desire of the Founding Fathers with respect to states rights.
They naively expected the gentlemen whom would be elected would follow that method and would stand aside if they could not follow instructions, and as we soon realized when it comes to power, being a gentleman can go right out the window. The first thing to go.