You cannot claim that people in NY State and California are oppressed, since their revealed preferences show them wanting to remain part of the federation. If people were unhappy with the current structure, you would see large and vibrant independence movements, whereas in actual fact those movements are a tiny fringe.
Despite its many problems, the US is one of the most prosperous, peaceful, and stable regions in the history of the world.
Without the Senate, the US simply wouldn’t exist (the smaller states wouldn’t have agreed to it), and North America would by now be a few dozen independent, competing, conflicting countries. It’s hard to imagine how that would be more stable than the current situation.
By the way, larger groups agreeing to give disproportionate power to smaller groups, in order to keep their union or federation together, happens all the time. Examples off the top of my head include Canada (where Quebec is massively overrepresented in the federal parliament), the UK (where England is the only constituent entity without its own legislature), Bosnia (whose three main ethnic groups split the Presidency equally despite having 50%/30%/15% of the population), and I’m sure there are many other examples...
The Bosnian example is particularly forceful, as this superficially “unfair” deal ended the bloodiest war in European history since WW2, in which more than 100,000 people died.