Poor Voter Turnout
Low voter turnout is often an issue that is brought up to criticize elections.  If only a minority of the population votes, and a minority of the voters determine the winner, then officials can be elected with only a small percentage of the population supporting them. 

Run-off elections fare even worse.  In many city and local elections a winner can only be declared when one candidate receives a majority.  If the general election fails to produce a majority winner, then a run-off must be held.  These subsequent elections historically have had extremely low turnout, with most voters not participating and thus further undermining the legitimacy of the election. 

IRV is a way to change this trend.  It completely eliminates the need for subsequent run-off elections by allowing voters to rank candidates by preference.  This was used with great success in the recent San Francisco city elections.  Run-offs previously garnered sporadic participation and added much to the cost of city elections.  Statistically, turnout jumped by over 300% with the introduction of IRV. 

[Read FairVote's report on the San Francisco city elections using IRV here]