Customer Service would Buy AT&T a lot more than Direct Mail

I recently began a quest to lower my television and internet bills.  I called my current provider to see what kind of deals they’d cut me, and unless I wanted to bundle with a landline, my cost-saving mission was not going to be successful.
It got me thinking about how often I see advertisements for home phone lines though.  And it kind of started to irritate me thinking the only way I could bring down my rates would be by giving them more money for a service I don’t need – a service many people don’t need.  I mean, does anyone have a landline anymore?  I could count on one hand the people I know with one.  Everyone has a cell phone nowadays, and most people I know use it for their “home phone.”
So why do they push so hard?  Every other day I get a postcard in the mail advertising for home phones.  Every time I call AT&T or Insight I have to listen to an on-hold message about how I need one.  Seems to me if they stopped spending advertising dollars on an obsolete service, and offered savings on the services I already have, I’d be a much happier customer.