IRV shortens the election cycle. Candidates only have to campaign once, and voters only have to pay attention once. The current system puts five months between the primary and the runoff. With IRV the result is known after one election. IRV reduces the cost of campaigns.
Candidates only have to raise funds once, and the county only has to pay for one election.
Most elections for open seats have resulted in runoffs - take the current Sheriff's race as an example. With IRV the public gets a majority winner with only one trip to the polls. IRV reduces negative campaigning. Since each candidate has to appeal to the supporters of other candidates for their second choice votes, there is less incentive to sling mud. The current system discourages many good people from running for office, because of the high probability of having to raise funds twice and campaign twice.