The fact that most people only watch a few channels doesn't really mean that a la carte would be cheaper overall.
Imagine that there are two channels. It takes a hundred bucks to keep the channel airing for a month. We have two viewers, A and B. A likes channel 1, and B likes channel 2, and they dislike the other channel. Right now, they each pay $100 to watch both channels, although they only look at one. Each channel gets paid $50 per bill.
So imagine that we switched to A la carte. Now A only subscribes to 1, and B only subscribes to 2. They channels still need the same amount of money to stay on the air, so what is the new price? subscribing to channel 1 is $100, and subscribing to channel 2 is $100 too. both channels get the same amount of money, both people pay the same bill... and they now get half the programming. Success?
So let's say that now ESPN charges $20 per subscriber. They do so, because they believe that the value they provide to the average subscriber is about $20. Let's say I don't like ESPN, Well, ESPN didn't get any less valuable, it's just that I will not pay the $20, and said $20 are going to be passed on as rate hikes to the people that want to watch the channel.
So while some people that really just watch very few, cheap channels, might get some savings, if your 17 channels include ESPN, Disney Channel, CNN, AMC and HBO, guess what? You will probably be paying a whole lot more than before, as unbundling makes every single channel more expensive, and you just happened to like 'anchor' channels that can really ask for a premium.