so-called deep-packet inspection devices, which can also be used to prevent piracy, the spread of malware, and website access, all at the Internet provider level....
Er, no, that is not what full packet capture devices are used for AT ALL.
Full packet capture devices are typically used for digital forensics. For example, your company gets hacked using an APT and you know that probably data was exfiltrated, but you don't know exactly what data was taken and you don't know how these guys got into your system. A full packet capture device can help here. Another way they are typically used is to produce evidence for court cases where employees steal company data and so forth, or browse child porn at work, etc.
They are NOT typically used to "prevent piracy" or "spread of malware" or "website access", I don't even see the use case here. I think the OP is confusing full packet capture with layer 7 application state firewalls, which ARE used for the above.