Why ask a question if you won't accept the answers? Would you also travel to a muslim country wearing a mini skirt? Or go to a wedding in torn jeans?
If you like it or not, there are some etiquettes still around, and wearing black (and not brown!) at a wedding is one in Germany. It is not only about showing disrespect to the deceased, but also the whole culture. It is not about if this makes sense in your eyes or not, it's about respect for a tradition in the country you visit.
But hey, go ahead, wear any colour you like, you will look like a fool, loose the respect from everybody else there and will be forever branded as the insensitive american. If that's what you want...

