You also have critics who think Apple is price-gouging us. If your universe of comparison is displays with lower resolution, then this might seem true. If, on the other hand, you restrict your comparison to 5k displays, it seems much less true.
A point of view might be that the LG was already overpriced to begin with (particularly given the woeful quality).
I think a better comparison is with the iMac 27", since this is basically an iMac 27" with a better webcam, speakers and backlight heat dissipation management, but without the whole computer and accessories, and for only $200 less.
I know there’s an “HDR400” spec, but is that really anything more than marketing? Most of the cheaper displays being compared are in the 350-400nit range. At that point, I’d say even if the display thinks it’s producing HDR, most people aren’t seeing HDR through all the calibration errors and screen reflections and such. The room needs to be awfully dark for HDR to really work well in the higher brightness iPPs. This display wasn’t made as a reference monitor expecting controlled lighting, they’re assuming those folks want the XDR. So what we get is a brighter SDR monitor which I’m quite excited about.
Strictly speaking it rather is a certification from VESA, not a spec per se. The regular HDR 400 certification seems to me indeed as a marketing gimmick as it doesn't feature any of the three major areas of advancement that makes HDR quite interesting (wider colour gamut, higher contrast ratio, higher maximum brightness).
That being said, maximum brightness, either full screen or only a portion of it, in my opinion is a grossly overblown fixation and doesn't ensure in the slightest a decent HDR experience. If your environment is rather dark and controlled, you probably don't need to go much brighter than 600 nits peak for a portion of the screen (and IMO even lower) provided the display still has a high contrast ratio - including local - something OLED panels are pretty good at. Most films are graded in HDR to be watched in such environments and it's very rare that the maximum value reaches 1000 nits as it's just too uncomfortable to watch anyway. Much more important IMO in such environment is that the panel can reach very low black values, is properly calibrated, including near black (big problem), has a wide colour gamut, and that the tone mapping preserves the artistic integrity of the content.
That's what the "True Black 400" and "600" VESA certification recognises. It's tailored made for displays capable of a high contrast ratio, including local, even with a moderate maximum brightness.
In a darker environment I'd rather be using such a screen than the pro XDR which local dimming isn't fine-grained enough to provide a good enough HDR experience (or even be used for grading applications IMO).
HDR isn't just about making stuff brighter, it's a lot more interesting than that, and the push to make displays better at rendering HDR content benefits SDR rendering as well for the most part.
I think it makes a whole lot of sense for Apple's HDR displays to target high brightness values (and therefore rely on LEDs + local dimming for larger displays) as most of them are portable, but I'd love to see Apple make an external, indoors display that deliberately forgoes high brightness values in favour of other benefits (such as an OLED / QD OLED display), at least until mini-LED can reach a high enough density to make this a moot point, particularly since Apple tends to be quite careful about factory calibration and that their implementation of HDR throughout their ecosystem is quite user-friendly.