It might be safe to guess that if Line 6 allows their guitarist at NAMM to only use a few amp models, and there are very few demo clips, that the device/models are still being perfected and not ready for prime time yet. And this is OK; many times a company will send an early alpha unit to trade shows to whip up interest.
I don't know if this adds up, though. Line 6 reps keep making the point that modeling a new amp takes as much as "one man-month" of effort. The Helix is scheduled to ship in 4-8 weeks depending on who you believe. So if it's not already packed with amazing sounding amps, they (and their customers) are in some serious trouble.
I think they just honestly believe that that (god-awful in my personal opinion) overdriven "plexi" tone holds some kind of universal appeal, and they haven't made it a priority to record anything else. I'm kind of operating on the "how bad can it be?" principle, given that I thought POD HD tones were "okay, not great", HX is likely to be at minimum a small improvement on HD, and the right IRs will go a long way to dress anything up. That, Line 6 effects (which I generally dig), flexible routing, and intuitive controller programming = worth the asking price (for me). If I had deeper pockets and more time with my guitar, I'd have a Kemper and a Helix... but I do not.