Yeah - I struggled with that too, but I think the killer app for iPad IS content consumption. I use mine for reading, taking notes, light games and media when traveling. The pencil was KILLER for me because I use GoodNotes and Notability for note taking, document review, signature and markup at work and nothing else comes close. Those things are uniquely iPad for me - although I can't really say that's the case for everyone.
I agree with you on content consumption, I actually have several iPads. The mini stays by my bed all the time because of the form factor. it's just easy to leave on the nightstand. The pro stays in the tv room because I tend to play games while watching you tube. I haven't gotten any use out of my Apple Pencil, perhaps I should try again.
Cost isn't the issue. I could get an AVP today (even write it off for business) but I don't know what I would do with it other than consume content. As cool as that might be, I don't see myself really wanting to do that beyond novelty. Same with productivity - it might be cool to use an AVP virtual display to do work, but I don't see how that's better than my really world dual monitor setup. My guess is that after the novelty wears off, it will just sit there and at that cost, I'd rather get something else.
After three plus weeks novelty hasn't worn off for me. And I use it in ways I just could not have predicted before getting it. It has replaced my iPad for content consumption and my MBA 15 for replying to email while watching you tube videos lol. Yes. I often have the tv on while using it. I read a lot of gripes about pass through video from people with unrealistic expectations, but for me, the tv (a 70 inch 4k oled) is good enough that sometimes I forget and try to move it with my fingers like it was just another AVP window. Yes, the APV is like a BIG iPad window (see what I did there? remember all the complaints the iPad was just a big phone), but instead of just one, its several. This is more useful than you might think. For example reading MR, will often have a link. On my iPad it changes the whole window, on the APV it just pops up another window. And I can have my mail or IM window sitting to the side. something pops up I pick up my keyboard and reply. It's a lot less bulky than an MBA 15, and somehow less obtrusive. I dont have a screen sitting in front of me, unless I want one. then I move it. anyway, bottom line is I prefer to use my AVP for many applications even if my MBA 14 and iPad Pro are sitting right there. Portability . I travel a lot and take it with me. Great for relaxing in a hotel room. etc.
I hope that AVP does find something for the masses to take interest, because that will drive investment and improvement. My wife didn't want an iPad when it came out, nor an Apple Watch, nor even an iPhone! Fast forward to today and she's attached to her phone, uses the Watch for all manner of fitness tracking, and can't fall asleep without her iPad. What I want is something that will make even someone like her NEED an AVP - whatever that might be!
I think this is going to be a slow boil thing because of the price, and I think Apple has planned for that. People don't get how very different and experience and use it is. So apple is seeding early adopters and developers for when the technology catches up to make it cheap and light enough for the masses. I did laugh at your comments about your wife... mine is so much the same it is scary. she would get on my case for why did I need the iPhone 1, then the iPad I, but she gave up before the Apple Watch came along. She would roll her eyes at me when I got them, saying she would never want one, but yes, today she too cant live without her iPhone, iPad, and Apple Watch. though she manages to maintain her dignity by not allowing me to upgrade her for years and years. Except for the phone, and I think its because of the camera, she will allow upgrades ever 2 to 3 years on that. As for the AVP, even when I debated whether to get it or not, I mean it is $3500+, she just rolled her eyes and said 'you know you will..' She does enjoy seeing my panoramas streamed to the TV, but has no interest in trying it. I do think she likes having more control over the tv remote these days. People will scoff, but 40+ years of marriage, and its enough to sit next to each other sometimes.