Personally, I don't wear a cross or have any pictures of crosses or any other symbols associated with Christianity hanging in my home. It tends to lead to images in our heads that we call upon during times of gladness or sorrow. I think people use it now because they've seen it for so long, they never question why they'd wear it. Some people will argue that it reminds them of His sacrifice for them. Others may say it reminds them to "take up their cross", but the danger in that is that it could easily become an idol without them realizing it. I can't speak for everyone, but many that I know wear it because they believe it's always represented Christianity and that they see nothing wrong with it. It's not a salvation issue, so I don't argue with Believers about it.
The verse that finalized my decision not to wear the cross was Acts 17:29 "29 Forasmuch then as we are the offspring of God, we ought not to think that the Godhead is like unto gold, or silver, or stone, graven by art and man's device."
Have a good evening