Encryption is basically free as far as I know, but it is more complex and it must be hard to get software updates up there.
> Panasonic told us that enabling encryption could incur a 20–30% capacity loss. In addition, when using IPsec, ESP and IP headers can introduce 20–30 bytes of overhead, which is nontrivial for small-packet applications like VoIP and video calls
Wow, I guess they're still betting on customers sending tons of redundant data up/down that they can shave off via compression? That's such a 90s modem thing to do. ("Faster than 56 kbit/s!!")