The question of paint on wood ship models is an interesting one, and perhaps worthy of a little discussion.
One of my predecessors as curator at the maritime museum where I used to work argued quite assertively that "ship models ought to be painted." His logic was that if they weren't painted, they didn't accurately represent real ships. During this individual's tenure, if the museum had the opportunity to acquire an unpainted ship model, he turned it down.
Another predecessor, several decades earlier, took a similar position to an even further extreme. The museum had a beautifully-executed "builder's model," dating from the 1930s, of a Japanese freighter. It was on 1/48 scale - about eight feet long. Like most such models from that period, it boasted a range of beautifully-machined metal fittings - winches, ventilators, railing stanchions, and so on. The paints available to modelers in those days weren't very good, so it was customary to plate the fittings rather than paint them. Most of the old bulders' models have nickel-plated fittings, but those of this Japanese model were plated in gold. In its original state it must have looked magnificent. But the museum curator, bluntly asserting that "you don't see ships steaming around with gold winches and railings," removed all the fittings and sprayed them with flat black lacquer.
Then there are (or used to be) those who, like C. Nepean Longridge, urged modelers "not to obscure your craftsmanship with paint." They argued that a ship model ought to represent an exercise in woodworking, and that anything but a natural, unpainted finish would spoil it. And there are, of course, the old English "Board Room" models. They generally have some paint on them, but large areas of them are finished naturally - and many of them have unplanked bottoms. (I know of at least one case in which a major museum, many years ago, hired a model builder to plank the bottom of an eighteenth-century Board Room model. If there's a purgatory for museum curators, I sincerely hope that individual is still in it.)
In my personal opinion, issuing any blanket, definitive statement on this "issue" is stupid. I sometimes like to compare ship modeling to photography. The modeler and the photographer both use technology and skill to create a representation of something real. But both of them, whether deliberately or otherwise, inject a considerable dose of their own individual standards, judgment, creativity, and taste into the process. Two shots of the same landscape, or two portraits of the same person, by two good photographers inevitably will look different. And, as anybody who follows the hobby knows perfectly well, two models of the same ship (or airplane, or tank, or car, or figure) by two equally-skilled and experienced modelers will look different.
There are lots of styles of model building. To label one of them "better" than another has always struck me as a pointless exercise. To decree that "all models ought to be painted" makes about as much sense as saying "all photographs should be taken in color." Would any art curator seriously suggest banning black-and-white photography?
Off the top of my head I can think of at least thirteen different approaches to building a model of, say, a nineteenth-cenutry clipper ship. (Painted? Unpainted? Plank-on frame? Solid hull? Half model? Waterline model? Full hull, with no masts? Fully rigged, with no sails? Set sails? Furled sails? Immaculately finished? Weathered?) I tend to get impatient with anybody who tries to tell me that any of those approaches is "right" or "wrong." To my notion what's more important is to understand the differences between modeling styles, pick the one you think is best appropriate to the particular project at hand, and within the parameters of that style execute the model to the best of your ability. If you do that you will, in my personal opinion, have built a good ship model.