If you don't want it, don't buy it. Great bikes are made from many different materials. For a multitude of marketing/engineering/economic/whatever reasons, carbon is where the mainstream of the bike manufacturing industry is focusing most of their development nowadays, so most of the commonly available nice bikes are made with carbon.
Steel is real and plastic is fantastic. Read this thread to see a retrogrouch's tale of stepping out of his self made box and trying something different (and loving it).
http://www.bikeforums.net/showthread...ic!?highlight=