... noobs won't and will be secured.
Noobs will scream when their router randomly restart (because it was just applying updates during their gameplay)
Noobs will sue mikrotik when the router breaks some config during update as they will wake up one day and device won't work...
Right now, people are responsible for setting and updating their routers. If router gets hacked, it is usually user's fault as some management interface was accessible from internet. Even vulnerable version wouldn't be hacked, if routers were properly set up.
Therefore, Automatic updates will not really help because properly setup router is not vulnerable. In addition, automatic updates will put responsibility on Mikrotik's shoulders. Any issue with upgrade will hit many people who will have no idea how to fix it.
Personally, I don't think it is worth it. (it might be, if all updates were without single issue, but it is getting more common lately, that upgrade brings some issues which needs to be addressed by person)