Well, take Van Richten's Guide to Ravenloft, which you brought up: you called it shallow and cursory, I find it sleek and useable for actual play.
Ah, but that's not true.
I've said that VRGtR is a mixture of stuff that's detailed enough, and other stuff that's cursory. I don't think VRGtR is intentionally "shallow", but it is necessarily cursory because they're jamming a huge amount in to an relatively low page-count. This is particularly a problem with the more-changed or entirely-novel realms, because you can't rely on older material if you're having difficulty getting a sense of what they're supposed to be like.
Re: "usable for actual play", that just sounds absolute nonsense to me. Like literally nonsense. There's no sense that you have a genuine belief in what you're saying and actually run/have run a regular VRGtR game (do you, even? I'm talking VRGtR not running Strahd, note), because you're not actually arguing it, you're just asserting it, and you're asserting something a fanboy would inevitably assert, whilst having a long history of being completely uncritical of WotC. So I'm unable to discern whether you actually mean this, or whether this is a knee-jerk reaction to criticism of a WotC product.
If you actually made an argument, and provided examples, rather than "running for the door" as I put it, it would be extremely easy to tell if you really meant it here.
As a general point, I've played and run RPGs for 33 years now, and I think I have a pretty good grasp on when I'm getting "my money's worth" setting-wise or campaign-wise. I would assert that people in general do not spend money on a specific setting to
not have details specific to that setting. This idea that people buy a setting but don't actually want any setting details seems pretty funny/fantastical to me. Obviously settings can go too far, but that's usually a very specific communication issue/customer requirements mismatch.
Look at Ptolus for example. It's a ridiculously detailed setting. Laughably. Wildly detailed. But it's much-praised. Why? Because the people who buy it want a detailed setting. That's a selling point. Whereas 2E's Forgotten Realms material was much criticised because a lot of it wasn't what people wanted - it was needlessly overdetailed when people wanted something more like Eberron's approach (to give a 5E example), or for that matter WotC's 3E FR approach. I don't really buy that someone buying VRGtR would be less happy if there was a bit more detail in the actual setting, like say, 33% more, maybe even 50% more. On the contrary, I think a lot of people who thought VRGtR was a "solid" book, like a 7/10 book, like myself, would have seen it as an absolute classic, had it been, well better as a setting book.
I think that'll be one of the legacies of pre-2024 5E - a lot of mediocre setting-books that aren't very good as setting books, and no exceptional/wonderful setting-books, at least not in WotC's output. The best of them are really Eberron (which is merely a recapitulation, just a good one), Theros, and arguably Ravnica. Again, there's time to change this, but they'll have to make a serious direction-change to do so. I'll be really interested to see the reaction from non-hyperfans to Spelljammer's approach.