After waiting for years to obtain a patent, and enduring a difficult path of expensive examination, the patent owner would have to endure still more attacks, without the shield of the clear and convincing evidence standard for protection.
Through supplemental examination, a patent owner can go back to the PTO after the patent is issued and voluntarily submit additional information to be considered as to whether it impacts patentability.
It makes sense that the value of companies is based upon the right to exclude all others for 15 years or more (U.S. patents are valid for 20 years from the filing date, but the examination process in the Patent Office will eat up a significant amount of time).
The PTO regulations demand that the patent owner not only submit the information for supplemental examination by the PTO, but also lay out in detail why the information might potentially invalidate the original patent.
The problem is that the PTO has proposed rules for implementing supplemental examination that would require the patent owner to mount an assault in detail on the validity of his own patent.