Between grades 5 and 12 my family did not have a TV. As I recall, it was a hard adjustment at first but after while, it seemed quite normal. Yes, there were times when I had no idea what everyone else was talking about, but generally, it wasn't anything that important. We all became more creative, learned to fill our own time, and read a whole lot more.
My hunch is that if the father-in-law wasn't on the couch watching TV, he's be on the couch reading, or listening to the radio etc. No disrespect to the man, but his argument is "It's the lack of TV when I was growing up that makes me watch so much of it now."
There's an interesting book Four Arguments for the Elmination of Television. (I checked, Amazon carries it.) It is not just a matter of not watching trash. Watching even good programing distorts our thinking, the argument goes. People begin to think and at some level believe that if they have watched something on TV, that they have experienced it. There can be no comparison to watching film footage of people climb frozen waterfalls and actually climbing a frozen waterfall, but we are willing to settle for footage of the experience and even think we now know something of what the experience is like.
Frankly, it's a little scarey that friends and family view this as a bad idea! It makes me think that they are slightly threatened by this prospect. I mean, it's not like you are threatening to take away their TVs! Reminds me of my sister-in-law. She criticised how we raised our kids - we breast fed, and then for way too long, no junk food, limited TV, required manners, used a family bed... we did nothing right. But then she would tell us and everyone else what wonderful kids they were... but we had done everything wrong in getting them to be that way! Go figure.
Go for it!