Let's put things in context. Would you trust WhatsApp to be part of the US nuclear launch chain? Or talkes between the leaders of US, France, China, and North Korea.
The type of encryption used in whatsapp is not something I want to authenticate in anything that has to be dormant and used in an emergency without a network, but that doesn't mean it is bad crypto.
Yes, why not? You still need to ensure that the people involved with whatsapp can be trusted, but even the NSA can't do that in every case (ie Snowdon).
