It was done to make the trim look beefier, can work on smooth drywall which you do not have. Nor do you have window casings.
It will be quite a mess of textures to remove any or all of it. Paint the ceiling same white as the crown, the rest of the molding that is "painted wall and the picture rail" below, to match the walls, and LIVE with it. You will notice it a lot less.: )
Actually.....two ways below. In both, CEILING as trim white, or whichever white you choose.
Q