I think if someone was suing me that re-examination taking a long time would be to my benefit. How much does re-examination cost the defense? Does the defense

I think if someone was suing me that re-examination taking a long time would be to my benefit. How much does re-examination cost the defense? Does the defense typically notify PTO which claims should be invalidated and why? Why does the defense have to do the PTO's job for them? I completely agree that the primary problem is too many patents issued for trivial, obvious or not-new technology.