Speaking as someone who did a year of dialup tech support.
For $199 they are probably making about $10 on each PC. A tech support call will put them in the negatives. If someone has a home network, then they already have a DHCP server. Plug in the PC and go.
But with dialup, there is a bunch of things to go wrong, and every idiot in the US has a phone so there is no chance of selecting down to people who have already configured a home network.
It makes sense.