Agree on MacBook v MacBook Air. I think the intent was to kill the MacBook Air and service the market segment it once occupied with a combination of the MacBook and MacBook Pro non-touchbar. However that didn't seem to work out the way they planned because consumers kept buying the old MBA, probably b/c MacBook Air also was the low-cost entry point to Mac ecosystem, and there's a noticeable difference between a 12" and 13.3" screen.
I actually don't agree about the XR v XS. Apple's in a situation where much of the market sweet spot for new iPhones exists within that $700-1200 range with a set of preferences around a 5.8"-6.5" size and expectations of certain features and capabilities. The smartphone market is gigantic and if you want to be a player in it at some point you need to differentiate the demand into two or more products, which means drawing the line somewhere in terms of price and features.
XS is 33% more expensive than XR, and the XR drops the dual camera and OLED, while being roughly the same size as the XS, plus a few things to lower cost. I don't know if there are other features you'd realistically want to cut, so it seems to cover the low-end of that sweet spot. The only thing Apple could do with it is maybe lower the price to $699. Meanwhile, I'm not sure what other tech the XS could add to move it further upmarket from the XR. I'm not sure I would have done it differently this year, given the available tech.
My guess from reading lots of peoples thoughts on this is there's a confusion in the relationship between size vs price. It'd be clean and easy if demand for larger phones correlated with willingness to spend more, but that really isn't the case for a lot of segments of that market. E.g. in China there's a preference for larger devices at lower price points. And there's also the quarter miss which is bringing a lot of these discussion up, which was mostly driven by China's massive recession, but fingers are I think unfairly pointing at the XR/XS lineup.
I've been watching the Apple product lineup closely for many years with a particular eye to market segmentation, and my take-away is that while Apple always strives to make it as easy as possible for consumers to choose their preference in product lineups, the fact is both the shifting cluster of preferences consumers have and the technology available to ship means most years they're off the mark by a bit.
Shifting a product line is a multi-year exercise and it creates anachronisms along the way - for instance, see the transition to iPad Pro in 2016-2018. It took a few years to sufficiently move the consumer iPad downmarket ($329) and the Pro upmarket ($799) to have meaningful distinction, and that had to be done incrementally both in testing the market's interest and in delivering on the key tech to do so. The iPad lineup during those years wasn't as ideally distinct as it could have been, e.g. the 9.7" iPad Air 2 and 9.7" iPad Pro both being sold in 2016 wasn't a big distinction, and the 12.9" was far afield from both. Then the next year the 10.5" Pro selling alongside the prior year's 9.7" Pro was also a bit weird, but made sense from a clearing out the inventory perspective.
When they were a smaller company, it was easier to distinguish market segments (e.g. Jobs' famous 2x2 of pro/consumer and desktop/laptop in 97), in part because they had to simply ignore many parts of the market, and because the tech was simpler and changed more quickly. I think the situation we're in now is in part because they went all-out on the X last year to create a distinction between regular and 'pro' models, and because rate of change in tech in general is slowing down. My guess is if they keep this going, in the next few years they will try to draw a bit more distinction between the two lines. The challenge to that going forward is much of the tech differentiation possible is now in software rather than hardware, and the whole zero marginal cost of software actually makes product segmentation harder.