I like that you like Mr.house but he isnt the best hope for hummanity all he really cares about is New vegas. If he would care about America then it would be different.
I don't care about America, I only care about New Vegas. Besides, NCR is already on that ball, so it's not like no one is trying to reshape the country for the better. Besides, NCR as it stands is stretched to thin as it is. It'll be some decades before they could expand en masse to the Eastern borders of all Nevada, moving further east.
Personally, I have the same field of vision as Mr. House, if it's within my little bubble, I want it reshaped as an image of splendor, a beacon of progress to inspire others into those footsteps. Outside it? Not my problem, I have no want to expand.
Edit: At least House is willing to be cordial with NCR, more than anyone can say of Caesars Legion.