How about "too big to not be public". It seems that there are some areas of thought (usually highly mathematical) that are virtually required to build anything else useful in a given field. Even based on a very liberal interpretation of the original intent of the patent system, it seems absurd to let a little clot of big business seize it and then rent-seek an entire society.
If ever there was a case where the exercise of Eminent Domain by government was required to prevent a tragedy of the commons from developing, this type of thing is it.
The funniest part is that MPEG-LA doesn't even gross that much money in license fees to get distributed to the pool — it's effectively peanuts for pretty much everyone paying in (only producers of 100,000 devices need to pay, and then it's pennies apiece with a total cap), and it's peanuts for all the pool members receiving the payments too!
They aren't directly hurting anyone's bottom line, nor is anyone really profiting from it. It's just a bureaucracy for FUD-maintenance, that was originally created to keep its members from fucking with one another.
If anything really gets out of hand, the government will just force them into a more liberal patent pool — it was done before to the Wright Brothers for being dicks, and in wartime to quasi-nationalize military IP.
The Wright brothers only got cracked down on because of a World War too. Hopefully we don't have to wait for such a dramatic catastrophe before the government reacts this time.
IIRC, Congress has the ability to void patents for the public good. Weren't such steps taken to standardize automobiles? And Hollywood wouldn't exist without piracy -- avoiding the patent royalties due to the Edison company was why they fled west to begin with.
If ever there was a case where the exercise of Eminent Domain by government was required to prevent a tragedy of the commons from developing, this type of thing is it.