The reason you get shot through walls, especially during sniper battles, is because you poke out and someone shoots you in the head, and it takes a second to register because of latency. High aim assist snipers in my experience have no more "bullet magnetism" than low aim assist snipers, and the majority of destiny YouTubers and devs are saying that aim assist only affects how well your reticle tracks its target, so I don't think that aim assist is the problem.