Patents are absolutely critical to startups and medium sized technology companies. Once a company becomes large enough that it's primary power in the marketplace is its size and cash, patents become just a nuisance. For companies like Google, Microsoft, and Apple, patents are just a necessary expense at this point, and they do get harassed by patent-holding non-practicing entities. If you had asked them if patents were important in the first 5-10 years of their existence, they would have said yes and very much so.

One problem is that, individual inventors on occasion do have valid and valuable patents, but when they approach a large company about a license, they just get blown off. They almost always do not have the money to fund a lawsuit, so the only way they can extract any value from their IP is to assign it to a non-practicing entity with the funds to do so. These NPO's are what are referred to as "patent trolls," but I'm not a fan of the term. I'm also not a fan of NPE's that file baseless lawsuits in an effort to shake down companies for tens of thousands of dollars just to avoid the cost of responding to a baseless lawsuit.