Couple of reasons. First, I dont think 2 megapixels is enough. I currently have a 3+ megapixel Canon and it is barely adequate in terms of image quality. I wouldnt consider anything less than 3 megapixels and I cant wait to move to six or more. Secondly, the phones typically have vastly inferior lenses when compared to standalone cameras from good manufacturers like Canon, Nikon, Lieca, etc. Third, the amount of control one has over exposure on the phones is virtually zero while on a good stand alone camera it is substantial.