I think the worst practical thing about software patents is that they create uncertainty. If there is one thing that is universally abhorred in the business world, it is uncertainty.

There needs to be a fast, cheap, reliable method by which small businesses can determine whether they are affected by anyone else's patent rights, and if so, by whose and to what extent. This way they can enter useful negotiations and adjust or abandon their plans as appropriate if patents are involved, or they can build their business free of unknown liability otherwise.

Given that I can see no viable means of ever constructing such a system, I don't see how patents or any similar legal tools will ever be anything but a tool for those with vast resources to crush competitors with few resources through means other than fair competition in the market.