I think you've probably got a point for optimal cornering, but it's also important for less skillfull riders to be able to move around on the bike more without being in danger of going over the bars in rough terrain. (as one of those less skillful riders, the new longer bikes definitely feel significantly easier to ride).
I struggle with this a lot. Mountain biking is probably the funnest thing I ever done. However, I still like rock climbing better, and put way more energy into it. If I hurt myself mountain biking, I won't be able to climb, which would be super hard. But mtb is so fun!
The contrast between climbing injuries and mountain biking injuries is kind of crazy too. Mountain bikers seem to break bones, get concussions, etc. I've had friends die in the mountains almost every year.
The other thing I'm curious about is how often people get hurt on techy jank vs flow trails.
But, I really wish they made one that somehow had only 10% drag in the descending gear and next to zero in the climbing gear, like the pinion. I would love to have a two-speed all-mountain commuter. I think it was a great idea, just badly executed.
I'm going to argue that market penetration was mostly due to the brand behind the tech, rather than the quality of the tech. They've also gotten reverb's on a lot of mountain cycles, and we all know those are utter crap.