Yeah, the lowest 3rd of the leg is only part of the suit. Her legs aren't that long. I haven't played much of Metroid. But I'm thinking about getting it for my 3ds. I think there's some Nintendo DS game(s).
There's only one DS Metroid; Prime: Hunters. I didn't play it but it wasn't one of the higher reviewed Metroids. Fusion on the GBA was outstanding. I suggest Prime, Prime 3, Fusion and Super as the best Metroids, not really in any order.
You can't see her feet. They are inside the part of the armor that is the "mid" part of the legs. If her legs went all the way down to the ground, not only would her feet be small, her lower legs would be freakishly long. So the lowest part of the suits legs is just machine.