What is the advantage?
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The main advantage is entertainment.
The Republicans always want reward the guy they think is the most loyal to the party and their supporters. I would say that this time, that is McCain. Before the convention, they will pressure the rest of them to give in, just as they pressured Reagan to give to Ford in back in 1976. and pressured Ford to give in to Reagan in 1980. No way Dole was the choice of the people in 1992, because the man was pretty much hateful, but he was one loyal lapdog.
The Democrats will probably wait until the convention to see how the votes line up.
We have a two-party system: that means many more will be voting against someone for some non-issue than voting for what they really believe. Previous non-issues have been gay marriage and the ACLU, neither of which actually will change anyone's life significantly one way or the other.