While the principle has validity, I do sympathize with those who worry that the federation-of-states system generates rather specialized minorities, and the reason for most of them is historical legacy with no particular promotable public good, even if some of them do promote such goods. I don't think we would create it this way today.

If you want to protect minority rights, other methods are possible, including requiring supermajorities.

You should not ignore rural voters, but does that mean give them more say than similarly ignored groups of urban voters? One would hope not. Thanks to technology, the costs of campaigning to rural voters has dropped, and the cost of casting (which I don't think is too tremendous) can also be made more level.