I've found that explaining movement (displacement) from the perspective of either front foot or back foot, could imply -- even if it's not meant that way -- that the "other" foot has a diminished or independent role. I prefer the approach where for example if I want to step forward or backwards, both feet/leg/kua are doing something; more specifically, they are doing the same thing but in opposite directions, which combined with whole body connection allows one to "move from the center".
That's a good point, any time we point only to a part
of something, in some sense at least, we diminish the whole
. So then I suppose that, while suggesting to move forward from the front foot might be a good way to augment movement which is coming too much from the back foot, it's only true until it's overdone in some way, in which case "use your rear foot more" might be the best response.
So, if there's a proper understanding (whatever that might happen to be) already in place to cohesively match the sides of the body to each other, I think it would make sense to use "part-oriented" phrasing.
I would guess that in all IHTBF things (so not necessarily talking about aiki here), "more this," and, "less that" are pretty common because of the real-time corrective descriptions being conveyed throughout the interaction. Another similar example would be "less shoulder," which is something I've been told multiple times everywhere I've trained (albeit I can count them on one hand). So I suppose the question is one of how much supporting information is also given to properly frame the "part-oriented" prescription.
I'm ultimately guessing, but in my own case, pressing forward with the forward foot seems like a good (presently better) way of keeping me from leaning and/or tilting my hips too far forward.