With Facebook's Messenger now being so much more than a mere instant messaging service, it's not too much of a surprise to learn that it may follow in the footsteps of the social network's other communications app, WhatsApp, by introducing end-to-end encryption. But according to a report in The Guardian, using this feature will come at a cost.

The publication's three sources, which it says are "people close to the project," say Messenger's 900 million monthly users will get the option to enable encryption sometime over the coming months. But unlike WhatsApp, encrypted messages will be disabled by default - anyone wishing to use the feature must opt-in.

Reportedly, message encryption will be optional because it interferes with one of Messenger's most publicized systems: machine learning. In order for some of the app's AI features, such as bots, to adapt and improve, they require access to users' messages and other data, which is routed through company servers. Should end-to-end encryption be enabled, this won't be possible.

Google is facing the same issue with its upcoming messaging service, Allo. The WhatsApp and Messenger rival will also have the option to enable encryption using its incognito mode. The company confirmed that it's an opt-in feature because activating it will affect many of Allo's AI services.

So it seems that users of both messengers will be faced with the choice of improved security and privacy or having access to the full gamut of AI features. Would you rather know that only the sender and recipient can see a message, or would you prefer to have better smart replies and virtual assistants?