I would agree that the cross has become nothing more than flippant jewelry and in many cases, a total mockery of Christianity. How many "gangsta rappers" or heavy-metalheads (Ozzy, anyone?) do we see going around "singing" about murder and drugs while wearing enormous crosses around their necks, or tattooing them onto their arms and backs?
Misuse of the symbols by those in "the world" is probably tangential, however.
The fundamental issue is the use of images in worship...but not just any images, of course. The prohibition against making and bowing down to "graven images" was linked to the worship of false gods...since the true God is invisible, any attempt even to make an image of the true God will become an image of a false God. It obviously flows inseparably from the first commandment--the worship of any other God than the God who created all things and led his people out of the house of bondage at a specific time in real space and real history. Ashera poles, Dagon statues, little metal dudes "that neither hear nor speak," that are either believed to be gods or (more realistically) to represent false gods are not to be made, kept, worshiped or served.
I would argue that the cross is in no way, shape, or form an image of a false deity. I suppose somebody could worship a wooden cross on a steeple. A converted environmentalist pagan could come into our sanctuary and be led into worshipping the fake tree up near the pulpit because their conscience is weak and they're still not over their old ways. The symbols, artwork, or decorations we have in the context of worship say much about our attitude toward God, as do all the things we don't have in the context of worship. An empty room with a chair still can contain a mountain of symbolism.
The cross, as a symbol, points us back toward the point when God's wrath and God's mercy met together, the pivotal moment of reconciliation between a holy God and sinful people. I think of that moment when I read about the cross in Scripture, or hear the cross preached in a sermon. I also think of that moment when I see a cross on a wall or a steeple.
I could be badly mistaken--and if so I would gratefully appreciate correction, as I certainly do not seek to worship God in an inappropriate way.