As Jesus tells us in John 3, He came into the world not to condemn the world, but to save it. Folks with scrupulosity often act as if God were looking for an excuse to send us to hell on a technicality. Probably bad horror fiction plays a role in that delusion, as well as sick, sub-Christian religion. But the real God because a human being just like you precisely to keep you out of hell. He lived those thirty-odd years on this planet for you. He volunteered to suffer the punishment you had coming for your sins. He literally went through hell to keep you out of it!
I won't go into the Christological and sacramental misunderstandings which cause many Protestants to dislike the crucifix. other than to say that it's strange that they forget that the same God Who forbade worshipping graven images also commanded Moses to construct two metal cherubim to sit on the cover of the Ark of the Covenant. And they also overlook the immediate context of the most beloved and most important verse in the entire Bible, the one about the brass snake:
And as Moses lifted up the serpent in the wilderness, so must the Son of Man must be lifted up, that whoever believes in Him may have eternal life. For God so loved the world that He gave His only son, that whoever believes in Him should not perish but have eternal life. --John 3:13-16, ESV
The crucifix can remind us of the very metaphor Jesus uses to describe the heart of his mission on Earth, of His entire reason for coming. Just as the Israelites who were bitten by the poisonous snakes God sent among them as punishment for their grumbling could be healed and live merely by looking with faith upon the brass snake God ordered Moses to erect in the midst of the camp, so sinners dying from the venom-filled bite of sin are healed by looking in faith to the Man hanging on the cross.
Not, of course, that there is anything magical about a crucifix; it's merely an ordinary piece of wood and metal. Nor does merely looking at it work forgiveness of sin, any more than merely the external act of looking at the brass snake saved anyone from the venom of the snakes. But a crucifix can remind us that Jesus came to Earth not to "get us" for our sins, but to "get us" to be His own. He came to be the One to Whom any sinner, no matter how great his sin or how long he has strayed or how often they have come, can look upon with the eyes of faith, and be healed, and live.