are we talking home router here or something more specialized?
A little more specialized. It's a sort of embedded system and it needs to fit within some size/thermal/watts/noise constraints. It needs to serve something roughly equivalent to a small office.
now if i needed a gateway/firewall for say 50 machines it would be different. dns, ntp, dhcp would all be moved to other machines on the network
This has to be one physical box.
