On the first step of a Waltz or Foxtrot to use the word Swing is wrong. If we were to Swing that step we woukd need a [sic] trench dug into the floor to be able to Swing the leg.
The error in this line of logic is one that I mentioned in my first post: Either (1) thinking of the swing as occurring from the knee joint rather than the hip joint, or (2) not accounting for the ability of the knee joint to adjust the shape of the entire leg independently of the swinging thigh.
If your supporting leg is straight, then as the moving leg swings at the hip joint, even if the knee were kept perfectly straight throughout, your moving foot would arrive at the same level when passing the supporting foot. In other words, it would be at the same level as the supporting foot, not below as though to "dig a trench". (I'm purposely not factoring in the shape of the foot from the ankle and toe joints to keep things simple).
When the supporting leg is bent, as would be the case at the bottom of a swinging figure, you would most certainly have to dig a trench if you wanted to keep the moving leg straight. However, at the moment the free foot passes the moving foot, the knee joint of the moving leg will be at least equally as bent as the supporting knee, meaning that there, too, the foot would be at the same level.
As for floor pressure from the moving foot, there are various schools of thought with respect to this topic -- some teachers believe in more, some less. I've already given my own opinion on the matter. But here's something to put in your pipe and smoke: If your goal is to maximize leg swing, floor pressure stands in the way of it... at least in the way I've defined swing. Criterion #4 states that it must move freely, not wholly controlled, in order to give the impression of swinging. The more resistance it faces, the more it will become bound and controlled by muscular force. So if you think about it, in order to reduce floor pressure, the knee joint of the moving leg should be ever-so-slightly more bent than that of the supporting leg during the moment of passing. However, this difference will probably not even be enough to be perceptible.
After all those years you would have thought that tha description of a Forward Walk would have been altered. It is in the Alex Moores Technique book Quote. Swing the leg forward from the hips. End of Quote.
You're assuming they're talking specifically about the narrow scope of a walk commenced from a static position. I realize they do begin by describing a starting position, however, I suspect the totality of their description is meant to encompass the action of walking in general. In all but the very rare walk from a stopped position, the legs are meant to swing on some level.
I do agree that starting a swinging action from the center position is not much of a swing at all -- like setting my son on a swing and pushing him from the bottom rather than pulling him to the top and releasing him. That first push is not much of a swing as I previously defined it. But likely they're thinking in more general terms. On most walks, especially those that continue one after the other, the legs do swing, and it's a good description of the free/unbound type of action you want from your leg, even when starting from zero (even if it doesn't exactly fit the pure definition).
Regards,
Jonathan