Why focus only on software
Patents might be a good idea for some fields of activity. The mass manufacturing of cars, and the development of pharmaceuticals in rich countries are two examples where some people think that patents can be a good idea. Why is software different?
For one thing, software is mass produced by individuals and groups who don't get paid directly for that work (or do it for non-commercial reasons). Adding the cost of the patent system is unfair to these people.