I agree. A $20 or $50 premium is reasonable for Y+. Half the price of business class is not, unless something significant is also thrown in. And to sell it, they will have to throw in something significant that is not offered now, not take away everything for the cheap fares and then say, "Oh, but you can have it all back if you pay twice as much." Perhaps some people would pay double for more legroom, free changes, and a sandwich, but I wouldn't.
WestJet's culture used to go well beyond having service-oriented employees who were empowered to make decisions. It used to include high value fares. The "About us" section of their website still starts with: "WestJet was founded in 1996 by Clive Beddoe and a team of like-minded partners, who believed that just because you pay less for your flight, doesn't mean you should get less." That part seems to be disappearing.