Ah, I think it probably is the price, though Apple's hubris may be the cause of them thinking a product at that price was ever a good idea.
If you're a developer, chase the users. AVP is extremely expensive, so there's not a lot of users, so not much reason for developers to care: even cheap VR hardware has problems getting enough users to justify the effort to make games (let alone other apps) work well on it. Even ignoring AVP, the whole category's sales are, what, mostly Beat Sabre? I think? You don't need a 3.5k device for a rhythm action game.