People that want openness and the freedom to tinker with their own devices will always find a way to do so, moving away from systems that inhibit their efforts (or just breaking them open, getting people interested in reverse engineering, an invaluable skill even as an open source developer). Others that don't care will continue to not care and buy the system that best fits their needs.
I think it's almost an egocentric worldview to demand that everybody use an open system even if they have no desire to make use of that openness whatsoever at best, and see it as a security/complexity risk at worst.
[1] By the way, both iOS and Android can run a full Linux userspace today!