It is definitely about cost. An SFP module for 1 gigabit copper ethernet is $20-30, and a typical consumer router has 5 ethernet ports. For $100-150 you can b

It is definitely about cost. An SFP module for 1 gigabit copper ethernet is $20-30, and a typical consumer router has 5 ethernet ports. For $100-150 you can buy a consumer router with 5 ethernet ports, a wireless card, and even USB ports (to e.g. host a storage server or connect to a printer).