Depends on what you mean by "Commentating" really.
If you're talking about TV style race commentating, broadcasters talking about what's going on all over the track, who is passing whom, distances between and wotnot then probably not. It might work on a replay maybe but it's probably not something that would be useful while racing, if anything it might prove more distracting. It works in sports games but I don't know that it would work in something like GT.
If you're talking about team commentary, say like a spotter telling you there's someone to your left / right or other actually useful information like that then yes perhaps that might be worth considering.