Software is great because it has no cost to copy, so when someone creates a new algorithm it can be put in use everywhere applicable rapidly. This pace of advancement is so awesomely powerful that many do not appreciate how much positive change it can bring or how different the world was just a few years ago. An advancement in algorithms becomes and advancement for humanity pretty quickly.
Software patents are the exact opposite of this.
I will take it one step further and claim that patents on the whole are bad. I don't think they do what most Americans think they do in terms of incentivizing inventors or protecting small business.
EDIT - Also software is already covered by copyright, why does this IP deserve two kinds of protection and most other IP gets 1 or 0 kinds of protection.