So that implies that a world power should be motivated by philanthropy rather than self-interest. That is very unrealistic indeed. Philanthropy simply does not exist - it is usually a cover up for tax evasion, fraud, or some form of social control.
The best we can hope for is enlighted self-interest - I help myself be helping you. Which, BTW, is the modus operandi of the US imperialism (and the x-USSR imperialism as well). The US occupations/invasions of Japan, Germany, Panama, Kosovo etc. were accompanied by attempts to reconstruct these countries - in a mold favorable to the US interest, to be sure, but that is the nature of enlightened self-interest. This is a stark contrast to the occupation/invasion practices of Japan, Germany, UK or France, and the score of African countries more recently, which can be summarized as divide, rule, plunder, exterminate, and leave the scorched earth behind.
The most annoying feature of US imperialism is its sanctimonious justification by arrogant US politicians - an empire in a poor style, if you will.
Wojtek