Well this is a type of television programming favoured by commerical TV stations who rely on generating revenue by advertising. These types of shows appeal to the lowest common denominator which means they dont offer a refined taste or opinion and so by default doesn't turn people off because its not to their particular taste. It also plays on the idea of voyeurism. This in theory means the show attracts a large broad range of viewers as possible which will in turn drive up advertising slot costs and make more money. This is often supplemented by a phone vote feature which generates more money.
In the UK, where the explosion of Digital Terrestrial Television has now given most of the public at least 30 channels to choose from, the big 5 commercial terrestrial channels have employed reality TV as a tactic to maintain large audiences. Most guilty of this is 'itv', nicknamed chav
tv whos last two attempts at reality TV were a little too far fetched (celebrity wrestling and celebrity love island) and concequently flopped.
My hope is that this represents a turn in the tide of endless banal reality TV and that the enormous amount of money made off it will be invested into quality TV programming but I think thats unlikely.