And to relate specifically to Instant Runoff Voting, IRV fails to satisfy monotonicity. It also fails to satisfy the Condorcet Criterion (a commonly held desirable property that the person with the majority #1 votes should be ranked 1st).

There exist `better' ranking systems such as ones involving markov chains (http://www10.org/cdrom/papers/577/), but I'd imagine that the Oscar Committee requires their voting/ranking scheme to be palatable to the general public. Using IRV is a good step in the direction of `better' voting, while still being explainable in a few sentences.