And those who buy it again chose to. If someone doesn't want BC on the console he can't buy it without (at least there haven't been options with or without being sold at the same time... well except old stock from PS3 when it transitioned).
1. If given the choice, most people would choose free, don't you agree?
2. This is parallel universe material. Are you trying to say Xbox owners are somehow paying extra for this feature? If someone doesn't want backwards compatibility, he/she doesn't have to buy/play backwards compatible games.