The two-assembly structure exists because it was a compromise to not give the densely-populated states all the power in the new Republic. Crucially, this sort of compromise was important because it helped the less-populated states get on board with the whole "federal government" concept without fearing that power over their own affairs would be continually swamped by places like New York. "Land" gets voting rights because those who were in charge of that land (the state legislators) wanted it in order to sign onto the project.
This is why I find the modern media complaints trying to do away with such structures very troubling. It may be more vestigial at this point, but the setup was supposed to emphasize a collection of states rather than mere administrative subdivisions of a faraway government. Frankly, if there would be any change to the state-based system for senators, it should come with a free ability for smaller states to secede as a group; because it would be going back on the deal.
And that's why New Hampshire needed senators. New Hampshire needed to ensure that it could still get the things it needed from the federal government (presumably money in most cases) to make New Hampshire a good place to live. That's why land has voting rights -- New Hampshire (using it as an example for all less-populated rural states) used to be a lot more sovereign.
Now things have changed. New Hampshire isn't just ensuring that it gets the resources it needs. Because most laws in the US are now enacted on a federal level, New Hampshire is deciding implicitly how /other/ states behave. And this is the problem, and is clearly against the intent of the Constitution ("any power not explicitly granted to the federal government will be left to the states").
So, the bicameral legislature as designed made sense. But in its current context, it's fundamentally broken. If we want to return it back to its original intent, then it's time to get back to a period of States' Rights.
That’s simply not factually true.
The South had an agricultural industry that was reliant (at least they believed it was reliant) on the horrid practice of slavery.
The Civil War settled the issue of slavery, and probably was the best time to try and rebalance the Senate. So now we’re stuck, and why would any of these less populated states give up power?
Looked at it that way, it makes sense that each state should have an equal number of representatives. After all, the federal system was supposedly created and maintained by the states. But after the Civil War flipped that around, and the 17th amendment called for the direct election of senators, they were really mis-configured for the job. As many people point out, now they're just direct representatives of the people, only with a mission created from the old ways of doing things. So why are they elected like this again?
As you say, we're stuck with it now. The only way to answer the criticism of giving states equal senators is to use an argument that is no longer valid. [Insert long discussion here about how nobody wanted a democracy in the U.S. It was never a goal and it was feared by the founders]
I wouldn’t say exactly they didn’t want it... but they definitely feared it. The presidency was also not directly elected, and now we’re dealing with that and the idiocy of the electoral college.
At least that one seems more feasible to fix, as the states themselves can decide how to allocate their electoral members.
I do wonder if the equal protections clause could be a mechanism to force a rebalancing of the constitutional senate allocation. I’m no lawyer, but it seems they they could be in conflict with each other.