They failed to come up with a strong selling point. Health is the big seller for Apple Watch. But AVP, at its price point, needs something better than "well you can watch movies on a big screen or work in a café while looking silly".
This leaves Apple and maybe a handful of subsidized third parties as the only people making applications for it, which is pretty much a guarantee that it will remain a tiny niche industry.
But I think Apple learned some things from the Lisa, even though it barely sold.
And even then I proooobably would've been able to justify it? But no external connectivity at all just sank it for me. Like if it had a DP port on it so I could hook it up to a gaming PC, I would've probably at least picked one up second-hand, possibly even new when my bonus hit but 3 large for... what? Email in my house? Movies shown in a way that makes it damn hard to eat popcorn?
But I guess the downside of the DK approach is it means telling developers when the “real” device will ship, which I’m not sure anyone knows.
Watching movies on a big screen would be interesting, but they still do not sell the device in my country in Europe, so I had no way to demo it and judge whether the quality is adequate for a home theater experience.
(I accept, I could book a demo at an Apple Store...)
I'm near-sighted, so I can see how magic glasses that let me focus on everything as if it's six inches away could be nice. That being said, normal prescription glasses work very well for my particular vision impairment, and "You only have to buy glasses once more ever, but they're $3000, weigh over a pound, and need to be recharged" isn't a great value proposition for my needs, but it doesn't take much imagination to figure that being able to toggle even just dark, high contrast, or colorblind modes irl would be nice for some people. Not worth it for me, but possibly for others.