This isn't my favourite depiction of the Emperor as it still gives him a regal and powerful air. one of the older images was better

It show the horrific state the Emperor is in much better, and in my opinion help to give a far more sombre feel not only to the Emperor but also to the Imperium he resides over. I think a lot of the more recent lore has depicted Imperium in far more powerful and united then the older lore has and this to me at least leads to a bit of a disconnect when they tell me the Imperium is is on the brink of collapse but then the artwork and stories depict the Emperor as this literal god, and the space marines and this endless horde of Primaris in shiny new armour bulldozing through waves of xenos and heretics.
Also as you can see in this image the Custodes are in black, which is by the old lore their official colour scheme in 40k, since after the 'death' of the Emperor they wore black as a sign of their failure (some of them also technically cast their armour aside, i.e. where the idea for pillar custodes came from in TTS). But GW kinda retconned that (sort of) because I guess people got to use to the 30K depiction of Custodes being these golden clad warriors... and maybe because many fans don't think of this tortured lump of flesh when they think of the Emperor but they think of the regal skeleton emperor on the throne this imposing figure, surrounded by gold and skulls so the expectation follow that his guards would be the same.