Earlier quoted context omitted.
I suspect it was the ISPs who made the decision, not the manufacturers. Removing the common excuse of "my network is open, who knows who did it!" for torrenting may be the reason. Another could be to make open/easily accessible networks rarer as they started selling Wi-Fi via the provided routers.
could be ISPs trying to improve user security generally to prevent lots of their customers becoming DDOS zombies resulting in more contention & customer complaints.
ISPs are unfortunately the problem, not the solution.