Results of a recent study revealed just why patent trolling is so popular, as the "business" cost US companies some $29 billion in 2011 alone. The study, conducted by Boston University, analyzed the effects of patent trolling, i.e. patent-related claims from companies/organizations that don't actually produce stuff, just troll those that do.
The study found that these companies are prone to taking higher moral ground by claiming it ensures inventors are compensated for their work. The trolls are dead certain this is a form of spuring innovation.
Authors of the study claim the aforementioned $29 billion figure only includes direct costs, such as legal fees. It does not include other, most likely even more dangerous and long-term consequences, such as product delays, market share loss, etc.
Irrespective of the fact that we're talking about direct costs only, $29 billion is a significant chunk of R&D spending. Apparently, R&D related spending amounted to $247 billion in 2009, which means that patent trolling has almost become a form of taxing innovation.