The Predator foot falls is lacking!!
Unfortunately not all legendary’s are created equal, which is why some are desired more than others. I do agree with you though. I think the effects of the weapon attacks should all be different (like they are), however the i think the footprints should all be the same size and drop on every step. I have Rodgort and see the same thing you are. I have passed it between several of my characters and believe it or not, they are larger and more visible on my little Asura than my much larger Norn.
Like Gator said, the legendary’s aren’t created equally (which I think is a mistake). Take the Minstrel and The Flameseeker Prophecies for example, neither of them even have footsteps/footfalls.