Flying is a commodity now and we all shop on price.  The airlines are walking on a knife edge in their treatment of their customers.  Air Canada and Westjet both provide unpleasant flying experiences, although not quite unpleasant enough to provoke full on air rage (with the exception of AC's 777 High Density, a truly awful airplane).  You can tell that they are seeing how close they can get to the tipping point without going over.

I don't know how overbooking relates to no-shows.  If you sell all the seats why do you care if not everyone turns up?  You have their money.