Just like other photographers who had (or have) big shows at MoMA or who are able to sell their photography for a lot of money Andreas Gursky has become one of the photographers whose work is derided by many people. I don't feel there's much need to address this. Regardless of whether you like it or not, elaborately staged or constructed photography that employs vast scales is here to stay, and comparisons with other kinds of photography (like "street photography", which supposedly is more "real") don't really make all that much sense.
