Agreed, it’s not sarcastic but wholly earnest. That’s not the issue, though.
As the first responder said, assuming the ‘White Man’s Burden’ is really supposed to be about assuming Imperial responsibilities. The question then becomes what exactly were Imperial responsibilities (then), what are they now, and, once identified, is “assuming” them reasonable (and not a tad patronising in the modern age)?
I think it’s fair to say that the line between (Imperial) responsibilities and, say, exploitation has shifted considerably since 1899, so that, even if Kipling did have a case, it’s difficult to apply in this age.
We don’t even have to identify exactly what Kipling meant (by his phrase) to see the line has moved as, since that time, dimension has been added by, for example, the advent of a more wary developing world, Marxism, maturing capitalism, globalisation and a greater understanding that Albert Schweitzer tinkling his Christian ivories wasn’t necessarily the answer to all Africa’s problems (though Albert was, of course, not British).
Indeed, and by way of example, if we substitute Schweitzer and his earnest belief in Christian values and Christianity with the religion of this generation of Imperialists (capitalism), the rewards of our imposing that aspect of the ‘White Man’s Burden’ doesn’t seem quite what it used to be; MTV, MacDonald’s, and consumption in general. At least the rewards to those on whom we impose our modern-day values aren’t what they were. We, of course, still gain believers/consumers/new markets.
Yet it all seems to come as a package; western style democracy means capitalism, capitalism means democracy. And a liberal, christian values democracy, as part of your bonus pack - just what the Muslim world ordered.
Thus, if we assume Kipling intended a moral and ethical dimension in his urgings to Roosevelt, there’s something of a problem in applying what he meant in the modern age in so far as our religion has changed (capitalism) and our motivations have changed (profit). The problem gets even bigger if those who are to subject to the White Man’s Burden happen to be sitting on a bloody big chunk of the worlds oil reserves.
Would Kipling be spinning in his grave? Maybe, or maybe his name (today) would be Paul Wolfowitz.