And there is every reason to be skeptical about Apple's ability to design even mildly complex crypto given iMessage's flaws. Although the break in iMessage wasn't practically exploitable, that was luck and the fact that the only way to detect if a mulled ciphertext decrypted required attachment messages. The cryptographic mistakes were bad. Given any way to detect decryption of mulled ciphertexts for standard messages (e.g. sequence numbers, timing, actively synching messages between devices, delivery receipts from iMessage instead of APSD), Apple's crypto design bugs would have eliminated nearly all of the E2E security of iMessage.
Remember, this isn't a boon for user privacy. Apple is now collecting far more invasive data about users under the claim that they have protections in place. At best it preserves the status quo and does so only if Apple both picked the parameters correctly and implemented it correctly.
At this point Apple's position should be best summed up as: we have drastically reduced your privacy except not because magic that we (i.e. Apple) do not fully understand.