There is no purely technological solution for the masses. Actually solving the problem requires either a political revolution to make shipping backdoors like this criminal rather than a favor to the government, or educating users enough that they can protect themselves with the existing technological methods that are easy to deploy given basic computer literacy. It's not really clear which one is less impossible.
Even making it criminal won't work - don't you know the NSA and the government are above the law. They have government endorsed hackers who are known to be actively exploiting these systems... but if you, Joe Public, are caught doing this, you're thrown in jail under the Computer Fraud and Abuse Act. So even if it is made criminal, it'll only be criminal for you... if it's government mandated, however, it's fine.
No its not. Installing Tomato or DD-WRT is only very slightly more complicated than configuring your router with non-default passwords, and you really shouldn't be considered at all computer literate if you don't know how to take even the first step to secure your network.
Take orders on Kickstarter for "open source router".
You order the Soekris boxes on behalf of the crowdfunders. You image your chosen open source OS on blank CF cards, bundle the CF cards together with the Soekris boxes and ship these to the crowdfunders as the "open source router".
If you want to bring a solution to the masses out of the goodness of your heart and you are motivated, then nothing is stopping you.
