This make no sense. Running Linux (or an OSS stack in general) is not what makes devices out of date. Not updating them does.
If updates are not automatic then the vast majority of people will not perform them. If they're not automatic and a pain in the ass to do (ever tried updating the firmware on a TV?) then even less will do it.
I'm not saying I want auto updates for everything (I personally don't like them though the option is nice) but for the vast majority of folks it's the right option. $NON_TECH_SAVVY_RELATIVE is not going to keep tabs on the latest exploits for her router and know when to login to the management console (assuming she can login) and apply an update.