One of the first questions we might ask is, Who decided that the cross, with or without a likeness of Jesus on it, was to be the sign of Christianity? This tradition of wearing a cross does not come from the Bible or the practices of the New Testament Church. Though there are at least seven different types of crosses, we are not even certain that Messiah was crucified on a cross-like apparatus. The cross symbol predates Christianity. The cross was honored as a religious symbol by the people of Babylon. Hey, if folks want to wear a cross, have one hanging on the wall, etc, that's fine but personally, I don't need a "symbol" to remind me of what Jesus did for me. :)
The only reason Scripture would forbid wearing religious jewelry, like a cross or crucifix or have one in your home, would be if the object became an idol used for worship. For some it does become an idol, venerating it instead of our Lord. Others need that symbol to remind them of what the Lord did for them on the cross. The problem with that is if they have experienced the saving grace of the Lord, that has changed their hearts, minds, and lives, there should be no need for any external reminder to help them remember. As always, just my opinion. :)
Suppose your only child was murdered with a pistol, would you appreciate it if someone handed you a miniature replica of the pistol so you can wear it around your neck? Most would think this a downright insult. Yet no one thinks anything wrong with wearing what the bible describes as an instrument of torture where the Lord jesus Christ suffered and laid down his life.