I know many Muslim cultures have henna as a staple for weddings. Its almost required that the bride get it done if she wishes to have a proper wedding. Henna through Bollywood has also become quite popular amongst the American crowd.
But it takes an American to find a problem with a practice as old as humanity itself. Here is an article from NBC that tells of the "henna hazard". (White people breaking out in blisters because of an allergic reaction to henna) This might have an impact on some brown people seeing that many eating and drinking in America have developed certain sensitivities too, as my grandmother complained about us Pakistani Americans whenever she visited, God rest her soul.