Because, for one thing, their executives live much too high on the, er, hog, already. For another, the whole organization is very political.
Shown, for instance, by their preference for visiting legally-convicted Hamas murderers in Israeli prisons while (until recently) ignoring Israelis kidnapped by Hamas, such as the young IDF enlisted man Gilad Shalit. They have asked to visit him but have never urged Hamas to free him. Why not?
When it comes to international charities, I much prefer the Salvation Army. The “Sally” performs its good works impartially, and its executives live modestly. Relative to the big time, big shot, and biased suits of the ICRC, that is.