I am a strong supporter of the patent system, and in general an advocate for software patents. This, however, is a likely example of an error. We accept a certain error rate in any process, and if the USPTO is expected to be infallible, then fees would skyrocket and people would complain that patents cost a million dollars. Anyone who tried to enforce this patent would more likely than not have it invalidated in court or on re-exam. Apparently the assignee (LSI Logic, hardly a 'troll') has chosen not to enforce this patent on Google and Microsoft because it is so weak. So before we grab the pitch forks, remember that the "system" as a whole has worked here, even if the PTO let one through. The tech world has not come crumbling down, Google was not shut down, and everybody who has ever modified a linked list has not been sued out of oblivion. If you have a much better method, I'm genuinely interested to hear it.
It doesn't matter. The non-zero probability of having to defend against this turd patent is real. Maybe the "owner" of the patent is reasonable and decides not to enforce it, maybe not. Maybe they sell it later and it is enforced. There is still a nonzero cost to this patent. The greater problem is companies see the PTO is willing to let shit like this through and therefore patent everything in sight. The "system as a whole" failed utterly here.
