Scratches are a minor issue because the induction surface is flat, as opposed to electric/gas which are not. A heavier dropped pan can also sometime shatter the glass surface of an induction range. And being heavier, a cast iron pan requires more electricity to heat. If you are cooking an egg in a 5-lb pan the vast majority of the power goes to heating the pan. A thinner/cheaper pan will heat faster, pass more heat to the actual food, and therefore use less electricity.