The only advantage I see is if it expands your TV footprint. Like if the Big 10 were to add Missouri, Pittsburgh, Rutgers, Syracuse, and say Boston College as a hypothetical, they'd get deeper into the St. Louis market and of course into the NY market as well as the entire state of Pennsylvania and the New England market, which would make them much more attractive for TV packages.
However, if they were to add Iowa State, Pittsburgh, Cincinnati, Missouri, and Louisville or something like that, I don't see what you gain.
It's got to be all about the TV package, otherwise I can't see the advantage of going for more than 12 teams and a conference title game. 14 or 16 simply means more hands in the pot, and if those extra teams don't add TV markets and enhance the TV deal, then it's just a further split of current revenues.
That's why I don't see the SEC expanding to 14 or 16, unless we could get into different markets, namely Texas or possibly Virginia or North Carolina, and I don't see that happening realistically unless this Big 10 shake up has a bigger fall out than I'm imagining.