Take a breath, mate. You seem to have run with a few assumptions on my intent. I'll try to clarify, and apologize if I was unclear.
By definition, there is no such thing as utopian America. It is merely an ideal (which the American Dream would seem to be, again, by it's very definition). It is impactful because it drives thinking and action in terms of steering the country towards this ideal.
My point is not that you should change your ideal for a second. My take, for what it's worth, are that all people are deserving of equal treatment, and a democratic society belittles itself when it treats citizens as less than equal. That's broad brush, obviously, but there it is. I find it disgraceful, for example, that my country (Australia) doesn't have marriage equality.
Basically, go your hardest. My point is that other people's conception of the American Dream will be different to yours, and will be steering their current actions. Think of a hundred individuals, each with a slightly different concept of the American Dream. All can be pulling for the same nebulous goal, but not pulling in the same direction.
I already covered this. I'm not asking you to validate anything. I'm suggesting that others will be pulling in different directions, but have the same broad concept of 'moving towards the American Dream'. To move the country towards your vision, you'll need to convince some of them that it's the 'true' American Dream, basically.
I think breaking up my post piece-meal is a good way to lose the forest for the trees, actually. But anyway, I am not asking you...at all...to change your personal American Dream. But if you are talking about how the American Dream drives action across the American society, then it's the individual members of that society who drive meaningful impact. It is nothing to do with right/wrong, or morality.
I don't care if you see it as naive, since it's not the point I am making.
Consider it this way...you have said that the American Dream is more around trying to be better than what you currently are. I completely concur. Lots of people would. That is not unique to America, but there are obviously unique elements to it.
Take a hundred people and ask them what that actually means, and you'll start getting answers roughly along the lines of what
@Father Heathen posted. America stands for rights, liberty, equality, and justice. No problem there either. Australia, for example, would believe that they stand for giving people a 'fair go' and for mateship, amongst other things. Obviously there won't be complete agreement, but I think it's reasonable to expect a level of commonality.
Try to apply those statements to a particular situation, though, and it gets very messy. Take 2 of those people who think America stands for rights and equality, and ask them their opinion on abortion...
My point wasn't that your Dream is invalid, or that the most valid Dream is that shared by the most people. It's simply that the majority can drive action or inaction more easily. If anything, it's a pragmatic/jaded view of the world. Sadly not a naive one.