I agree with Brendan, the point is not whether we can change the colors or not, it's whether or not new viewers and newbies that don't know it can be changed can view the art as intended or not.

I also know what he means by working against the dark background in your art. It's a matter of white balance and how your eyes percieve the values of an image. If it's a predominantly dark image, as many renders are (because they start in darkness and are lit, much like theatres),they tend to lose a lot of the detail because of the white drowning out the darkness. It's the same as trying to watch an outdoor play with lighting in broad daylight versus at night. Art in brick and mortar galleries usually start on light canvases and are made darker, so they play better on white wall.

I really hope in 2 months or whenever, they consider switching the default back to some dark color, maybe not black, but something in that range (and please not mid shade gray)...

My 2c