Because the shell UI is not application UI; the idea is: 1. to visually distinguish the two contexts; and 2. to ensure that the shell UI doesn't dominate on the application UI, as you're more likely interested in the latter than the former.

These two principles have been there since GNOME 3 was first designed.

@ebassi I mean for consistenct they both have to talk to each other, selecting light mode should make everything including shell and other stuff same .. Otherwise it's all disjointed n inconsistent.. But I digress..

"Consistency" doesn't necessarily imply "everything looks the same regardless of intent". It can also mean: "things look and behave differently to achieve different results". This is one of those cases: the difference is intentional.

@ebassi Oh ? Well just to clarify I am not hating on #Gnome, I made lat clear in my video. But I guess am so used to #Plasma's more customizable way of doing things. Now to just get over that VM issue where mesa n Mutter don't play well with each other causing UI breakages all over..