Very few people actually do each year in relation to the number of viewers so if that was the sole aim it would have scrapped years ago. I assume that they make more than enough from voting and so on to make it worth their own while to produce a new series each year so the sales of the winners single probably doesn't matter to them in the grand scheme of things.

If Cowell has any sense he'll go back to a Saturday night final and release multiple versions of the song for download. Both of those things would have changed this years Christmas number 1. McElderry fans were handicapped in being restricted to 2 downloads, the campaigners had 5 versions to download twice giving them 10 downloads each.