The reporting you're talking about has been widely denounced by actual security experts, with 70 of them signing a letter asking the Guardian to retract its inaccurate story. Your position is about as responsible as saying "I don't trust vaccines, they kill people".

http://technosociology.org/?page_id=1687

Get off the FUD brigade.

It's not FUD: it's just a threat model WhatsApp and those experts do not care for, or alternatively think is a worthy the UI/UX trade-off.

FWIW, I strongly disagree with this stance: if the recipient's key changes while the message is in-flight, that message should never be resent/delivered without the sender's explicit approval. Imagine that Bob is a political activist planning a protest. Bob is wondering why his IMs to a co-conspirator Alice aren't being delivered; Bob's wonder turns to fear when he hears on the news that Alice has been detained. Fear turns into terror when Bob sees his messages subsequently get two blue ticks as WhatsApp happily delivers his IMs to a new phone belonging to the secret police. Only afterwards does WhatsApp notify Bob that Alice's key has changed

OWS never claim that Signal provides anonymity. The word they use is privacy which sometimes involves being anonymous, but not necessarily so.

> Wasn't whatsapp all over the news for its "replace the encryption key transparently without notifying the user" feature ? Also facebook.

Which was a conscious design decision. Not doing that (even for people that had turned on "notify on key changes"), would let whatsapp know which users could be securely MITM'd. Neither is a very good choice, but an understandable trade-off when it comes to security vs usability.