Think about the public policy implications of that rule of law. It would mean that the use of the IP and manufacturing needs to be done outside the US in order to avoid the patents granted in the US.
This would favor foreign companies competing in the US and drive US companies to move their violation of US patents outside the US (off-shoring work).
None of those cases are similar to the Momenta vs. Teva case and I certainly don't think that Momenta's IP is worthless, rather I wanted to show how the courts increasingly have expanded the scope of the safe harbor provision. Patented research tools may well fall outside the safe harbor exemption.