Yeah I see what you mean... But I believe they did it like this on purpose.
One of the main themes of the game is the stark contrast between the decadent life of the wealthy and powerful and the horrifying places they created for the less fortunate to sustain their power. (factories, slaughterhouses, the machine...) It reflects how morally rotten they are on the inside while keeping up a facade of beauty and decency. Dishonored has a similar approach btw. Therefore, I think that thechineseroom aimed to make the contrast between the two "worlds" as striking as possible: One is clean, well-lit and tidy, the other one dark, filthy and chaotic.
On a more gameplay-related side, this contrast is also needed. If the player was to explore run-down dirty areas all the time he'd get used to it and they would lose their effectiveness. But by keeping the two sides in stark contrast they always feel "fresh."
In a nutshell: I'm sure we'll get to see dark and dirty environments as well as nice and bright ones so don't worry too much about it
edit: Hm looking at the screenshots again, some parts of the machine environment seem pretty tidy as well. Maybe they wanted to symbolize the cold efficiency of the machine? Or maybe its to create contrast again... make you stumble from a nice room with golden tubes into a chute full of blood and guts... who knows.