Do you really think Han cares if his ship is super bright? As long as he can see, I imagine he is just fine.
But when you love something as much as he supposedly does, you care for it the way Lando did.
I would also like to point out Lando’s yellow seating upholstery. *cringes*
Agreed. I don't see Han bothering to change it.
"canon" reason - age. The Falcon has gotten older, its a smuggler/tramp freighter so the repair and upgrade money goes into the import stuff, like shields and engines, and the internal lighting is dim and dark because its mainly non-functional.
"real" reason - expectations. Look at the space ships of the 70's and early 80's. They were always dark, poorly lit, dingy, how ever you want to describe it. This is largely because THEY DIDN'T HAVE REALLY COOL, LOW COST LEDS! LOL Well, actually, it was because they wanted it to be dark. You're in SPACE! They wanted it to feel like the inside of an Apollo capsule.
As Logos said: it doesn't 'feel' like a spaceship. Why? Because we grew up with dark interiors on space ships. The one exception being the Enterprise. That ship is always brightly lit. LOL
I would argue that the Nostromo had alternating light and dark areas, but the light areas were very bright and white. Same goes for the ship in 2001. And the original concept of the Falcon was this:
I always loved that about Star Wars; the ships in that universe were varied from sleek to utilitarian. It was ok to have an dirty/ugly ship.