Why so many posts on Instant Runoff Voting? For a few reasons. One is that what we have is called "First Past the Post" (fptp) or "winner take all" electoral system. This system tends to gravitate to two parties. This is known as Duverger's Law.
Our current system is defended in its simplicity. That sounds to me as an insult to be able to understand more than two choices. We expect people to understand lots and lots of choices when shopping, but not for something as important as who leads us to war. Very interesting and sad notion.
Often our style of system leads to single party governments. Wait you say, we have two parties right? Well we actually have many. But there are only two national parties and often on has a strong majority over the other in our type of system. Like the Republican Revolution we have just survived we now have a Democratic Majority. Well, after that what will we get? Depends on what organizing we do NOW.
Disadvantages to our system is that it actually excludes different voices. Since the set up is that a vote for a new voice or party will not likely get the plurality (most not always majority) of votes they are seen as "wasted" votes. So in our system voting for who you REALLY want is considered a "waste."
On average our voting system excludes minorities from fair representation. People may think we are past that now, and in NM it sure doesn't seem to be the case. But look at the range of political thought considered part of our norm and you'll see that minorities can mean many different things.
Women are also often excluded in our system. Around the world women represent 11% of national elected officials in fptp and 20% in proportional representation systems. This and a lack of general responsiveness is enough problems.
With a fptp system you get a lower voter turnout and much less responsiveness. If you don't need a majority to get elected then why bother being responsive? Democracy requires responsiveness. Democracy needs participation.
If we made a minor adjustment and went with Instant Runoff Voting, we would still have some problems but they would be much reduced. With IRV you would need to be careful of attacking another politician because you would want to be that politician's constituency's second choice. You would have to try and come to a true center in order to win elections.
Minor parties would be able to become part of the debates and elections without being a "spoiler." This spoiler effect limits our debates and dialogues and thus our real choices. We think in the US that we have a "left" and a "right" yet we really have a right and a center. A whole range of thinking is missing.
We would greatly improve our politics if we could encourage more choices. A democracy needs many options to be true. The millions it takes to run for national office, the limitations on who can run for that alone is shocking. Then take into account who doesn't even bother to run because they don't want to be a spoiler and we have a truly limited democracy. This one simple step would open the door to better ideas and greater participation. And that's what democracy is all about.