Well, ask and ye shall receive. Commenter Festinog over at GWBWYPGN?! gives us this credible explanation:
One should have been a UN led Policing Action (which is VERY different from a war, not just in terms of its mandate, but how it is actually enforced on the ground), the other WAS a unilateral military invasion.
And that's it. What was needed in both cases was international forces marching in, the world united against what amounts to the forces of evil, to defend those in need of defense and lawfully remove all of those individuals - be they Rwandan rebels or Hussein's entire government - responsible for the atrocities in question. What was not needed was a unilateral action by a Western president grown too big for his britches, who went in unprepared for the sheer size and responsibility of such an invasion.
Had the US responded to news of the genocide in Rwanda by bombing the everliving crap out of the country, killing many of the people we intended to save and leaving the country with very little infrastructure worth rebuilding, we would have ended up with what we're facing now in Iraq: one group of grateful survivors, another group of seriously ticked-off insurgents, and one really awful reputation in the world. We can't change the past, can't change our actions or lack thereof. But we can - and should - learn from the past, and that involves cooperation with a coalition of the enthusiastic, not just the willing, and the realization that destroying a village in order to save it is a pretty crappy strategy. We can't ignore evil when it crops up in the world, but we also can't respond with such overwhelming force that when we're done, there's no one left to save.