I do think there's too much focus on the hands when trying to get the horse to go on the bit. That sawing motion that so many people are taught just doesn't do it for me, I think it looks awful and it can't be nice for the horse. With some horses, the more you try with your hands to make him lower his head, the more resistance he gives you. Many horses, once working nicely from behind with plenty of impulsion, will then drop their head with the slightest of play from the rider's hands.
I ride one horse who will stick his head up like a giraffe and go tense throughout his entire body the second you get too firm with your hands. With him you simply have to get a nice forward-going trot, then, keeping the outside rein constant, give the inside one away - he will drop his head immediately and go into a lovely outline, and as long as you take back the inside contact quietly, he will stay that way.
As TEmily says, any horse can benefit physically from being ridden in an outline, but for your average leisure rider I don't think it's necessary to work the horse like that all the time. Even with dressage, if you're competing at the lower levels, outline is not the most important aspect of riding a good test - circles that are circular, straight lines that are straight, and accurate transitions will get you good marks even if your horse does little or none of the test in a decent outline.