I disagree. First of all, the MacBook Pro does have 'mainstream aspirations' - and it's been selling in the millions for years. Sure, the iPad Pro and XDR and, maybe even the Mac Studio fall into the 'niche' category, but you're still comparing Apples to oranges: all the Macs can run the same software - so as an application developer the ENTIRE MAC base is my potential market. Similarly with the iPad Pro. So Apple doesn't have to worry about getting developers to adopt those devices. But with the Vision Pro, Apple clearly does and it has a chicken-and-egg problem.
Besides, Tim Cook clearly has much greater plans for the Vision Pro than it does for some Mac or iPad variant: he grandiosely talked about a whole new computing platform - spatial computing! There's no way something this grand was meant for a tiny market - Apple is a for-profit corporation, so with that much investment in R&D it clearly hopes to sell in the mass market - maybe not with the initial version, but eventually.
You clearly have no understanding of segmentation and extremely disingenuous when those other product categories have mainstream variants while Apple doesn’t yet offer such a thing yet for their spatial computing portfolio.
Macbook Air and Macbooks are the mainstream options for laptops; Macbook Pro while selling millions is not (especially compared to the whole laptop market making your statement naive).
Also the laptop product category is a much larger and mature product category.
Cook is talking about spatial computing platform holistically—not just the Vision Pro.
He also made sure to clarify its positioning to people as yourself arbitrarily making up success metrics he and Apple doesn’t even have for the device.
Apple has historically even launched a prosumer device first before mainstream before; it seems this time with how much more prevalent social media is to give anyone with an opinion a voice a lot of insecurities are voiced about the potential prevalence of such devices or people with no need to be early adopters—which is fine and normal.
Not everything Apple releases needs to be mainstream or have mainstream fanfare.
Apple correctly doesn’t solely seek that out with their excellent series of prosumer products that often don’t have much competition for the most affluent and reliable customers of a device category.
Different product categories grow at difference paces and they certainly don’t have to be targeting mainstream users first.
Heck that was the case of traditional computing in the first place with many on here too young to remember that and don’t know their computing history despite the museums and etc that makes sure this isn’t forgotten.
Spatial computing is fundamentally more expensive, exclusionary, and harder to pull off than traditional computing. None of this push back is even a surprise to many.
Tech illiteracy is prevalent though; it is what it is.