Good work, but like you say - does BC really matter? Well it hasn't helped MS close the gap on Sony from what we can tell so I'd say not really.
Don't forget Sony used to do the whole BC thing and decided to drop it after they looked into how much people used it.
I think it's a great thing to offer though...I've always backed BC and hope nextgen has it too.
Isn't it disingenuous to say BC doesn't matter because X1 isn't selling well? There are a lot of reasons for that, none of which relate to BC (which X1 didn't even have until 2 years after launch). BC came too late to make a difference, as the generation had already been decided.
Also, I genuinely don't believe the value of any one feature can be based on Console sales alone. For example, going by your logic, since N64, GameCube, and Wii U all sold poorly despite having great exclusives, that must mean exclusives don't matter, right? Also, since Pro and X aren't selling as well as the base Consoles, that must power doesn't matter, right? Oh, and Wii U was cheaper than PS4 and X1, but sold far worse than PS4 and X1, so that must mean price doesn't matter, right?
You know as well as I do that all of the statements above are false. Price, power, and exclusives all matter, but none of them sell a system on their own. It is a combination of these things that sell systems. So why then do you say BC doesn't matter? Can it sell a system on it's own in spite of said system's numerous other failings? No, but that's all X1's sales prove. They do
not prove BC is meaningless.