There is also the argument to be made for getting a candidate that more people are happy with.
For example, with a ranking system (very simplified):
candidate A: #1 choice for Repubs, #3 choice for Dems
candidate B: #1 choice for Dems, #3 choice for Repubs
candidate C:#2 choice for both Repubs and Dems (100% of people) --> Winner
So then the question is, is it better to have someone most of the people are OK with, or someone who is HATED by 49% of the people?
Are you saying this is what would happen under IRV, or are you proposing a different system all together? If it is the former:
Candidate C actually wouldn't win in this scenario under IRV, but it is a bit too simplistic of a scenario to serve as a good example.
Remember that people's first choice IS their vote. It is only if no candidate receives a majority that anyone's second choice even matters. Therefore, in this scenario, 100% of the vote is split between A and B since no one chose candidate C as their first choice. Unless A and B received exactly the same number of votes, one of them would win outright.
Even if there were a tie, candidate C would be eliminated as the low man, so he would not win. However, in this scenario, there would still be a tie, because candidate C had no votes to be dispersed to the other candidates when he/she was eliminated. Realistically, this would probably never happen except in a very, very small election, like a 5-10 person precinct. I'm not sure how they tie would be broken if this were to somehow happen to be honest.
What could happen in real life would be that candidate C, aside from being the second choice of all of the Republicans and Democrats, could also get a lot of independent votes. If he got more votes than, say candidate A, then candidate A would be eliminated and all of his votes would go to candidate C, since that is the second choice of all of the people that voted for A. This could put him over the top for the win.