The heads are too low in pleasure, a lot of the time. And they SHOULD be disqualified for it with the new rulings, but judges like to look the other way. ;)
Once the horse breaks at the withers, the weight falls on the forehand (unless he's lifting at the base of the neck like in a 'long and low' dressage frame--but then he wouldn't be 'breaking' at the withers, either). It doesn't matter if it's natural, or not--My horse LOVES plodding around with his head by his knees.
And it doesn't make it okay. This isn't about 'unnatural' and 'natural'--this is about good performance and bad.
In order for the horse to transfer his weight to the hind end and move in a nice frame for showing, his neck HAS to be level, or he has to be lifting at the base of the neck (which you hardly EVER see in a WP class). Judges are beginning to place horses with more level necklines--not because of the height, but because those horses 'look better'. Because they can carry themselves in a better frame.
You'll still see stupid trainers TRAINING the horse to put it's head down below it's withers, but it's slowly being phased out.
By me saying that they move naturally, I don't mean they naturally drag their noses on the ground. I mean that they naturally have a more level neck and can be easier trained for WP.
I think that how a lot of WP horses are trained/bred are based on what the judges are placing. I am glad to see (at least at local shows) that the horses that are carrying themselves well seem to be the ones that are placing rather than the ones going super slow and low.
Wasn't directed at you, Spastic Dove. ;) I don't appreciate the 'he LIKES to move this way!' comment when a horse is practically kneeing himself in the face with every stride. :P Doesn't matter if he likes it, it's still WRONG.