That’s where we’ll have to disagree. States, as incarnated by their state governments are ostensibly supposed to have the best interests of the entire state in mind. Most states have two situations where equating the interests of the state to the interests of the people is incorrect.
First, many states are not homogenous. They typically have a large percentage of their population concentrated in urban areas. But the state government has to look out for the rural residents and as importantly from a whole-state perspective, the industries and agriculture of the entire state. So the policies and decisions that would affect the state as a whole don’t necessarily track with what the majority of the people might prefer. Much like having the Senate in the first place relative to the entire US in that sense.
Second, while individual voters may be intelligent, informed and contemplative in their approach to voting, the general public is about as logical and well-informed as your average 5 year old. They’d probably vote for John Cena if he ran on a “I’ll Iron Claw Vladimir Putin” platform because he’s “bad ass” or something equally dumb.
So having the Senate chosen by state legislatures puts the popular idiocy at a couple of removes, and sets the stage (ideally) for senators to be more contemplative and less concerned about the hoi polloi and more about the nation in general.