Ultimately it's because the US is a bad compromise. The original intent was for the US to be a loose confederation of somewhat independent countries similar to how the EU is currently structured, however the civil war showed that some of those States couldn't be trusted enough to not treat their citizens like shit so the federal government had to be strengthened. This reduced it from a loose confederation into a mostly centralized government but with a bunch of territories that function more as testing grounds for stuff that isn't quite ready to be promoted to the federal level.

The Senate is an awkward leftover of that transition. Under the original design it somewhat made sense, you could even argue that the House was the bit that didn't quite fit under that model because every State was supposed to be equal to every other one. The thought was if you didn't like the State you were in you could just move to another one. Slavery of course disproved that theory.

Under the post civil war design of the US the Senate is now the piece that doesn't quite fit because the people are supposed to be the ones in charge now with the States being an awkward hold over from the earlier confederation concept.

So yes, ultimately it probably makes sense to eliminate the Senate and strengthen the House. It's either that or you fundamentally restructure the powers of the US government again. The States have demonstrated that they can not be trusted with civil rights so at a minimum you would have to make civil rights the exclusive domain of the House leaving things like economic policies and trade to the Senate. What we have now is just awkward and doesn't really work for anyone, the civil war was never really handled properly and it's about time we cleaned up from that properly instead of taking a bunch of half measures and kicking the can down the road.