True, it wouldn't work just throwing that in this year with the current contestants, since most of them entered solely because they have strong vocals. But it could make it interesting if they set that up for the next season, letting everyone know when they start advertising the auditions, that one of the live shows will be based on songwriting. Might change the crowd it attracts, and start seeing actual talented musicians entering the show, and less of the crap we've seen in the past who, once the show ends, release an album of cover tracks, then disappear.
I think with the viewing figures of both the American and British versions apparently beeing on a downward slope, it is important they do something to change it up soon. This would at least add some credibility.