The problem being: patent trolls like Lodsys LLC do not actually create anything. There's nothing to countersue over.
They don't sell products, but they surely use computers internally. Which makes them vulnerable to all sorts of patent lawsuits.
Patent law lets you sue both the person making the software (Microsoft etc.) and the person using it, in this case Lodsys.
But if it were, anyone setting up a patent trolling company would be targeted at future companies as well, which is a very concrete disincentive.
Ex patent trolls would basically run the very real risk of being unemployable, and have trouble starting legitimate ventures as well.
- Filing a frivolous lawsuit makes the plaintiff liable for the defendant's legal expenses.
- Repeatedly filing frivolous lawsuits can get you labeled as a vexatious litigant, and if labeled as such you need a judge's permission to file even a valid lawsuit.
- Lawyers knowingly participating in frivolous lawsuits or vexatious litigation can be disbarred.
For these reasons, I don't think you will see corporations filing a lot of meritless nuisance lawsuits.