Because it's a universe destroying bubble gum who makes black holes into child's play. And their basis on Kirby's strength is like putting Bugs Bunny to Superman.
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I'll be the last to be called a reliable source of Naruto lore, but I have never actually seen Garra's sand move as ridiculously fast as people suggest. Be that an animation flaw or what, I dunno, but Garra didn't seem to be the kind to go for the quick kill. And their reasoning after the initial opening, well, it makes sense to me. She controls his weapons, his environment and even himself with greater ease than he does. He losses the advantage he had by not blitzing.
I think you might be looking a little too much into the pillars though, it's simply the chosen available sprites that looked nice. If you need anything more, she's a kid, kids show off, and it takes no additional effort to make than a simple large rock for her.
The wire I get, it was just rather poorly executed. Would have been better skipping it altogether and have her draw the needed elements out of the ground to make sturdy enough armor, rather than stretching a steel wire around herself.
To be honest, it seemed stretched out myself for Toph's position, she doesn't need to touch him to change his armor. As long as he's connected to the ground and it covered on it, she could have done her own sand coffin. But I suppose what they did is good enough for me.
Basically, I seem to wonder a lot why they never go for the simplest, fastest kill. Yet would likely get annoyed when their fights are too short.