People want it for torrenting or hosting things to the outside world. /c/Piracy has been flipping out because Mullvad removed port forwarding, which now apparently makes them one of the worst VPNs ever.

Mullvad (and I’m sure others) removed it because individuals have frequently used this feature to host undesirable content and malicious services. They simply do not want the kinds of things that users were hosting, passed through their servers as it has led to police visits, blacklisting and providers cancelling them.