Cable Sales Guy: "Do you want to rent a router?"
Customer: "WTF is a router?"
CSG: "You need one to get internet on your computer"
Customer: "I guess I'm renting a router then"
Cable Sales Guy: "Do you want to rent a router?"
Customer: "WTF is a router?"
CSG: "You need one to get internet on your computer"
Customer: "I guess I'm renting a router then"
The marginal cost to me is a minimal amount in electricity. However, their policy of doing this allows them to provide me "free" (included in the cost of my internet) WiFi basically everywhere I go. The cost savings of not needing to use my more expensive cellular data easily outweighs what I am spending on the margins to support this scheme.
The only reason I don't do this is because I use my own router (and modem); so now I just freeload off of everyone who does.
I will say that the public hotspot usage doesn't count toward your data cap, at least.
It's as if your neighbor also had WiFi running.
there may be reasons to do so but is the cost one of them? It is probably infinitesimally low.
Basically, it's a feature Comcast offers which is paid for by the ignorance of a percentage of their customers.
Customer: "sure, how else would i enjoy my new shiny internet access?"
CSG: "so the more expensive router with WiFi enabled option it is"