Its not really that port mirroring is "bad".
Its bad if it can be remotely switched on via a back door and pointed towards destination of choice.
No technology is bad unless used in a bad way.
Well… I guess its also bad if its use to seamlessly funnel every single bit and byte of data running across a major trunk in two directions simultaneously. One towards destination that serves the consumer and the other for real-time ingestion at line speed and later analysis elsewhere and calling it a feature of the unit. I don't think privacy is a privilege, but rather a right. No one has to be licensed for privacy. Its not something that you should have or not have at the digression of the government or anyone else.