I mostly disagree with your post.
But not because you said something stupid. Much rather because I see the market in a different light.
The incredibly vast majority of all touch users, doesn't have any interests in keyboards or sliders. With a slab phone, BlackBerry has a competing offering for those out there who aren't brand loyal ("competing" is an euphemism here. BlackBerry doesn't exactly have the greatest ecosystem and app store).
With a slider, BlackBerry has... Another strange form-factor the entire market has completely rejected since the OG Droid.
I personally love sliders. I'll pre-order that phone from Amazon the day I can.
But... Let's be honest, sliders sell even less than pure keyboard phones. And they already sell damn badly.
In every poll/from what most devs say (in the BlackBerry/CrackBerry World), it's obvious that people prefer the all touch over every other form-factor.
If it's a high-end device, or a good mid-range device, probably isn't that important. We do know however, that Z10/Z30 users don't have an upgrade path. The Leap is not an upgrade. It's a Z30 with extended warranty for 250$.
So, if you personally have the impression that people on here don't demand a high-end device that much, it's probably because those have decided to move onto other platforms, instead of playing the waiting game.
I think that this is much more of a reason, than people not wanting one. "We" just accepted that BlackBerry won't produce a phone for "us" (well, they gave me a slider. But I'm not 99.9% of the market).