I agree that there's a sense in which a dollar means more to a poor person than a rich, but that sense is not an economic one, but one of morality or cognitive science.

I would have phrased it differently - I would have said that the standard economics is just wrong here, but it doesn't matter for observable implications of preferences, so they can get away with it. I'm not sure if this means I disagree with you or not - it may just be semantics.

edit: I should have said observable behavioral implications of preferences. There are, in fact, neurologically observable implications of cardinal preferences, but the fact that preferences are cardinal doesn't have an impact on the behavior of an agent. Well, at least if we assume that agent is rational. Now that I think about it, there's the potentially a nonrational agent that's a counterexample to this statement.