The reason this should be done as it is the law, pure and simple. I, by law, have the right to know what information/data a company holds on me. If they wish to collect data in the first place, and are a reputable company, they should be well aware of the "obligations" they have before then even start collecting it.......Why do they want my information? What do they plan on doing with it? Could it then end up in the hands of anyone who could do with it as they please?

Much the same way i wouldnt want to be contacted/emailed/telephoned/written to by companies i have in no way solicited to contact me....