Haiti doesn't have much to begin with - if cruise ships stop there, that is at least some tourism dollars going into the country and some of the Haitians have jobs and are getting paid from it...
Losing the tourism dollars & port charges doesn't help Haiti any... and if the cruise lines are willing to deliver supplies... that's a good thing.
One of the articles I read quoting some of the passengers said that a lot of them were making sure to buy a lot of the local crafts from the market without bargaining to try to contribute more to the economy.