I agree that BC is important to the family/casual segment. My kids play the Wii titles I have as much as the Wii U titles. I did move the Wii upstairs but at 7 years old I'm not sure how much life it has left. So for the time being they can Just Dance upstairs or down and in a year or 2 they can still Just Dance even after the Wii dies. That's pretty nice. Of course if it died I could probably get a used one for $50 or so but that's a pain and costs more money.
Considering the failure rate on X360 and to a lesser extent PS3 and their higher cost that's even more a concern I would think for those parents if there is no BC. A family maybe has 15 or fewer titles and would like to keep playing them and the 15 or so they end up getting on the next generation. That family may not be the most critical customer at first if Sony is selling at a loss, but it may become one if that family's kids become the next fanboy that buys 100 titles and never switches.
If that ecosystem effect is gone it's also easier to switch between 2 consoles. So if someone is 50/50 between PS4 and X720 but already has a PS3 then with BC it's far more likely they lean PS4. Take away that link and there is no reason not to switch. If it's technologically feasible Sony should allow the PS4 to detect the PS3 title is inserted and stream the game for free - in effect giving true backward compatibility versus just having PS3 titles available in some sort of subscription or repurchase model.
I don't think BC will make or break the generation for any one company. If MS also isn't backward compatible it may help Wii U next holiday season as parents decide whether to take the leap or hold out until MS/Sony drop their price since their kid seemed to want PS4/X720 more.







