A 'ranked ballot' might also ensure that the end up with the most bland candidates who will accomplish the least.

In Canada we have used forms of 'ranked ballot' or multiple ballot elections for party leaders in the past, even if we haven't used them for general elections.  One key example of what I'm talking about is how Stephen Dion was selected as party leader in 2006.  In the first ballot Michael Ignatieff was easily the most popular candidate with Bob Rae second and Dion a distant 3rd with less than 18% of the vote.  Similar story in the second round of balloting where Dion managed only 20% of the vote and was still a fairly distant 3rd place finisher.

It was only when they got down to the 3rd and 4th round of balloting that people, grudgingly, decided that they would prefer the 'bland' Dion over the more controversial Ignatieff or Rae.

Another potential problem with ranked ballots is seen in Australia where they have reduced elections to a de facto two-party system.