I think people who do miniature painting themselves have some ridiculously high standards.
Maybe... But I expect paintjobs on-par or better then what we get on actionfigures, from say... McFarlane, Bandai, or JoyToy. (as it doesn't have any moving components)
When I cough up the money for a $400 Tiamat I don't expect that wings and tail only fit with huge gaps. Or that the heads they glued on have gaps still. The paintjob highlighting on the wings is just a bad drybrush that looks streaky on that huge expanse of wings. I do not expect a Golden Deamon painting level colossal mini/maxi at $400, but I do expect better painting then that green dragon you showed, the white dragon looks a bit better (skin/eyes). It needs to pass the table test, not the zoom lens test.
Compare that to a $400 JoyToy figure of Angron Daemon Primarch of Khorne, which actually look like the promotional images, and is made to be played with and can be posed (has multiple different hands):
World Eaters Angron Daemon Primarch of Khorne
Compare these minis with the ones WotC used to make for D&D or Star Wars.
You mean compare it to a WotC Icons: Colossal Red Dragon from 2006, $60 at release?:
Gallery of Pre-Painted Plastic Miniatures Images and Pictures for Roleplaying Games like Dungeons and Dragons, D&D and Pathfinder
www.minisgallery.com
To be honest, when I look closly at both the $400 Wizkids Tiamat and the $60 WotC Colossal Red Dragon, the paintjob on the old, far cheaper WotC mini is just better. Sure, there is no highlight (aka. bad drybrushing), but at that scale with the proper colors and paintjob, you don't really need it. As it's big enough for natural light to actually do it's thing.
And then there's the price, at release the minis were $10 per booster, they had 8 minis (4c/3u/1r), including small, medium, and large minis, the price later increased to $13. Currently a WizKids booster goes for $20 each and contains only 4 minis, 3 small/medium, and one large. And while WotC did get bigger booster packs, that were more expensive, they had huge minis and still held 8 minis. Since 2003 the inflation has been ~75%, which would explain a price of $20, but with only half the minis. The Wizkids sets are also smaller and have repaints within the sets as well that further limit the sculpt variation within the set.
So from my perspective, the price of minis has atleast doubled, imho the paintjobs are worse in many cases, and the material seems to be harder (thus more brittle) thus tossing them in a bag is less of a good idea. For me the price per mini during the WotC era was such that it could excuse the lack of quality paintjobs to a certain extend, that also made the minis less valuable, so I could toss them in a bag or box and transport them in my backpack to the D&D session. Today I'm more inclined to complete my old WotC D&D mini collection then start a new Wizkids collection (beyond the few huge/collosal dragons I already bought).
Generally, at the time of preorders there is no printed sample yet they could show. Usually 1-2 months before release, the Wizkids store page gets updated with photos of a prepainted copy, or they share them on Twitter or Instagram. For example, photos of the Pathfinder Adult Diabolical Dragon just got uploaded on Instagram yesterday.
But it's still not up on their actual store page, where they should be. The render though looks absolutely gorgeous!