I wonder if the polish aristocracy liked colourful horses (as opposed to later british units, which prized uniformity) for the same reason — to make it easy to form (and especially reform) their squadrons?
> In 1943, someone came up with the idea of selecting a war weary bomber from each group and providing it with the means of clear identification—additional navigation lights, pyrotechnics, and a wild unmistakable group-specific paint scheme. Signal lighting systems vary from group to group, but generally consist of white flashing navigation lamps on both sides of the fuselage in the form of the identification letter of the group. All armament and armour has been removed. These ships will not go all the way to the target, so they carry minimal fuel and a skeleton crew of two pilots, navigator, radio operator and one or two flare discharge men. A few groups require an observer to fly in the tail position to monitor the formation. They are the first from each group to take off and they orbit the assembly point, flashing their lights and firing off coded flares until all their charges can find them and form up on them.
So the assembly ships are called that because they serve as an assembly point for the fleet and their garish colors are for better visibility as they're not meant to be involved in direct confrontations with the enemy and merely lead the way.
Some of the skins look like dazzle camouflage on WW1 battleships, or the false canopies painted on some modern fighter jets. I wonder if that was at least part of the idea (e.g. confusing German fighter pilots) besides giving the bombers a unique look.
(PS: apparently not, instead to quickly identify the special 'assembly ship')
eg https://d-art.ppstatic.pl/kadry/k/r/1/c2/ce/63ee71cd24172_o_... , as opposed to https://upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Sc...