I don't know what lessons can be learned for Haitians. When disaster strikes an area of such abject poverty that even those who would like to be prepared have neither the means or the ability to do anything about it, it is indeed a desperate thing.
I feel sorry for the poor folks who don't and never had, a chance. I won't go into the politics of it...
I guess the one thing we can take away is if this type of disaster were to hit a large population center in the US, similar situations would ensue. It should be a wake up call to all of us that maintaining some level of foodstuffs and water would be adviseable. The whole 72 hours is way too optimistic. I would guess it would take that long to really mount an effective disaster relief effort of any magnitude. I would say 14-30 days preparations are probably more in line with reality. Additionally, I would probably bump that up a bit because I would have pity on friends and neighbors not so far-sighted and make an effort to help them if I could. But that opens up a whole new can of worms and philosophical debate as well.