I'd be happy with a global setting to choose between the old or new appearance.

Thanks for the link to the FFF. For me personally, I find distinguishing entity types to be quite important, and didn't have a hard time spotting ghosts vs non-ghosts with the old visuals. But if this change is popular ...

TL;DR
Some ghost and real entities are very hard to distinguish by colour, making manually building a blueprint difficult. I think the graphics need to be tweaked to make this clearer.

What ?

Can you tell these assemblers apart by colour?
assemblers.jpg

They are:

Top row: all assembler 2 ...