I guess it at least stops the constant questions about job security for the coach. If you know you're gonna fire him, do you have to give the fake vote of confidence?
Also, on the other side, an interim coach is an awful thing. If he strings together a few wins, then you'll be on the hook a lot of times to hire that guy. And other than Dabo Swinney, that hire almost never works out. USC almost had to hire Coach O a few years back when he was the interim guy there. And didn't Clay Helton get the job there the same way a few years later?