But it's not extortion. It's perfectly valid and legal. The client list is entirely comprised of huge corporations that could afford to fight frivolous patent suits. Do you think that as soon as they get a letter from a "troll" they just mail a check?

Also when you phrase it as "Technology companies agree to pay patent-licensing fees to inoculate themselves against potential lawsuits by Intellectual Ventures." it sounds like extortion. Another way to phrease it is "companies agree to pay patent-licensing fees because Intellectual Ventures owns the valid patents they are infringing on."

You can phrase almost any perfectly moral activity to sound like extortion by using the same trick. "I pay taxes to inoculate myself against potential lawsuits by the IRS." or "I pay rent to inoculate myself against being evicted by the landlord." or "I go to the grocery store to inoculate myself against starvation." Is the grocery store extorting me?