Without getting wrapped up in semantics my definition of a fad was different, perhaps wrong even.

Motion controls for the Wii for example was a development in technology much like CD or DVD, but it was also what overwhelmingly sold the Wii to 25 million people a year. People who had never owned a games console prior or since. It's hard to dispute that because what else sold the Wii to that many people? Take motion controls away and you're left with a Gamecube in another box, it would have flopped hard. Now to be straight, I don't think the PS1 and 2 sold because of CD's and DVD's, but apparently some think they did. And that being the case DVD's would be (my definition) of a fad. Perhaps the wrong word to use, maybe 'selling point' would have been more accurate. The technology itself isn't the fad, it's the novelty that it created that is the fad.

I think BC at the start of a new generation is paramount. 3 years in it's not that big of a deal.

Come PS5 and XB1X2 BC is going to have to be there, and at 100% compatible to PS4 and BX1, not what it is right now.

Oh, for sure. Even though it's been done before with the PS2, Wii, Wii-U, DS line, and to a lesser extent, the PS3, it's still going to be the "new" paradigm going forward. The piecemeal, hodgepodge, after the fact approach currently being employed by MS, while laudable, is not even close to the same thing as absolute, 100% BC out of the gate.

Geez. Those are some pretty big "if's". :) But they did what they did. With a big, shit eating grin, Don Mattrick smile backing it up. Who then told people who didn't like it, that the Xbox 360 was still there to meet their needs. An audience who almost exclusively already owned that console. I know Hitler analogies have become passe, which is huge loss for comedy...... but, if only he had focused on the autobahn, anti-smoking legislation, and his paintings......

It makes me cringe in all sorts of ways...

But yeah for the few people that replied that I'm over simplifying the events, of course I'm just picking the key moments that turned me personally as a Xbox fan to a Playstation fan (I still buy every system lol, just mean fan as in the one I'll start up first at home) but yeah I know that events to begin the generation don't mean the whole thing is going to play out that way, but for everyone who watched that reveal the same as me was basically -1 from the X1 sales and +1 to the PS4 sales. Now you have that online environment to think about when it comes to games too far more than any previous gen, so if you want to get the system your friends got and play the same games as him, even if they're third party games, chances are by order of the early lead... your mate will likely have a PS4, as such that's another sale of the system.

I am pretty sure the absolute majority arent buying it for the motion controls

Yes. It's something that still exists in a vestigial state, but it's hardly what it once was. Which is the only outcome that was possible, given it's obvious limitations.

Again, on a site so driven by numbers and data, we have a lot of "we knows" and "I thinks" involving this issue, but no real solid numbers I've ever found have ever really helped affirm the common belief that you're holding. That was pretty much entirely my point. 

Using motion controls as the core central mechanic for gameplay is a fad.

Using motion controls as a supplementary mechanic for gameplay, however, is not.

PS2 would have still sold at least triple million without the DVD playback. Take out the motion controls on Wii probably would have sold a little better than GC.