There are many cosmetics in Sea of Thieves, but with their being the main way of showing and accomplishing progression, there should likely be many more. This goes for both the depth (customizations of different parts of the ship, character, etc) and the width (different options for one part) of the options. Past completing and releasing the cannons, capstan and wheel of several neglected existing ship liveries, such as the shark hunter, Forsaken Ashes, or all faction-based sets, and completing and releasing many unreleased clothing items for existing sets.
For ship liveries, there are many new places for cosmetic options to be implemented. We could have:
Lanterns: Be they mimicking the handheld variants, changing the default ship-mounted ones, or completely different versions.
Railing: Ranging from damaged and repaired ones to flawless and pristine ones.
Rigging: Such as chains of different materials or extra bits of rope, fabric, leather or other things hanging from them.
Crow's nest: Mimicking the railings in terms of being rebuilt from complete or partial destruction, or being somewhere from perfectly to badly preserved ones.
Compass: Some, like the lanterns, being the handheld ones mounted to the ship, while others could be variants of the normal ones, and still others completely unique.
Harpoons: Likely being similar to the cannons in appearance, or even just included with them. Preferably not the latter, however, especially given the lore of ships such as the Magpie's Wing not even having them.
Bowsprit: This large beam could be changed into anything to a decorative ram matching the figurehead to a broken and bent boarding plank, though little change to its hitbox or function should be made, I believe.
Other things, such as customizations which do not have to have an equipped version at all, could be made as well. These could include:
Hull/railing plating: One could choose to mount decorative plating of varying materials and designs on their ships (providing, of course, that it provides no advantages in terms of speed, maneuverability, defence, etc).
Decorative banners: These could hang from the bowsprit, the spars, the flagpole, the rigging, even the ceilings. Some pirates would put as many as they can anywhere they would fit, after all.
I have few other ideas for this, more would be welcome.
Equipment, or 'trinkets' as the game calls them, would likely welcome many additions. On top of some sets, such as the Ghost, pirate legend, Ferryman of the Damned, etc not having all that they should, more items could be added to use. I have few suggestions, other than the long awaited violin and perhaps some form of handheld bell, though I fail to see too many interactions or uses the second could have. An instrument, I suppose. Suggestions welcome, but these are quite well fleshed out. I do not think customization of the individual items should be added, as many of the variations of the cosmetic versions fill this role.
Clothes and vanity items are a colossal section when it comes to incomplete sets, particularly the shirts often not being given to some, so that I'll leave to Rare to deal with. Some sets do work better without one, but the more options the better, and some players may, and likely will, prefer to have it. As for other options of pieces to use, there could be:
Switching pegs, hooks, patches and dominant hands: Some players would prefer their pirate to match their dominant eye, hand, or anything else. I've seen some ask for two peg legs to be an option as well, inspired by their first encounters with Merrick and his two peg legs, alongside asking for the hook he uses being a bent nail in a small piece of wood. As for having two hooks, or two eye patches... I'll leave it to Rare to figure out the logic of that.
Necklaces: Though some could be a far cry from those of the Pirate Lord or the Forsaken Shores Alliance, amulets and necklaces would likely be a welcome addition to the Sea of Thieves, be them for a pirate to identify with their favored company or pastime or for a crew to match without sacrificing their preferred clothing.
Earrings: These, and by extension nose rings, which some would definitely ask for, would be great to better show the personality of a pirate. Some love to decorate themselves with more than just jewelry, others prefer very much not to.
Rings: Ranging from small bands that might not even be made of metal to well-made circles of precious metals decorated with ornate icons, these could show or signify a vast amount of things and not fit very well over or under some gloves. Some crews could use them in the same others would necklaces, some not at all, and others simply collect and wear many at a time.
One final expansion which fits into this theme is of the curses. We need more curses. Curses from different sets, such as an ocean themed one covered in starfish and barnacles for the curse of the Wailing Barnicle, or a skeletal arm reminiscent of Wanda (the Order have claimed it to be only cosmetic, and not a sign to worry of transformation into a skeleton lord) for the bone crusher curse, even something transforming the character into a ghostly apparition for the Ghost curse, unlocked from many difficult commendation completions.
Weapons are the most complete of all sets, with most sets other than a few (shark hunter, for instance) including them, and all that do including all four. I won't be suggesting other types of weapons to add here, but should any further actual sets be added for other things they should include weapons.
