Noone's ever going to build a secure device if people are fed such snake oil and given the impression that they have "some" or "enough" security if they use it.
The point is, they get 0 security and we should not pretend that they are getting more. We are ripping off consumers if we do, what we think they want is a poor excuse, unless we're just in it for the money/fame/other benefits.
Software like this is about making mass surveillance more expensive. If you have a backdoor or a remote exploit for a phone, you might still be able to wiretap somebody, but at least all data on the network is encrypted.
Apparently I'm fighting windmills here, but encryption does not work on compromised devices. It will be sabotaged and rendered ineffective. Google for DROPOUTJEEP, what makes you think you can keep the encryption code safe from manipulation?
Try building a secure device that users "own" first, then spend effort on building secure services on top.