Everything you said is 100% true Alric. However, as much as we are each responsible for our own safety and fun, I believe that we are as much responsible for the safety and fun of our opponents. So moves that have a high ratio of injury, compared to other options, should be avoided in most circumstances.
With one leg out, a legged fighter can twist an ankle. With both legs down, a legged fighter can roll over backwards, digging his boots into his back and possibly causing injury to his ankles and knees. Not to mention there's the fact that a lot of people seem to just think it's perfectly cool to boot someone in the teeth, or have that level or horrendously bad aim.
That said, feel free to shield-kick me when I'm legged. I talk enough crap, and have fought long enough and had enough experience that if I don't know what to do, I deserve to get twisted up. Just don't kick me in the face, or I'll head-butt you in the balls, or... something...
As far as walkthroughs go, I'm probably not the best person to describe them, but I'll do my best. The point is simply to walk through the opponents as if they are not there. This is highly effective both in line fighting (as a group), and against legged fighters. Then you hit what's open, usually shoulder/chest or arm. When you get to the fighter, pin their shield with your foot, or kick it out with your shield. At this point they're pretty much at your mercy. The key is to stay active and aggressive, moving forward consistently without moving wildly. It keeps the legged fighter on the defensive and limits their mobility, which is key.