First off I’d like to say I understand the Value of having been there the first time and earned something to show for it.
Once enough time has passed it should not matter anymore, if given the correct application.
Removing Cosmetic items that were Time-Limited, in a game comprised of only Cosmetics, can be very disappointing enough to make players take time off for awhile.
For example I did not have enough doubloons at the time to purchase the Wailing Barnacle Capstan & Cannons.
Giving players an extremely Costly and Lengthy grind to earn many of the previously removed cosmetics would give veteran players even more reason to continue playing after each update.
This would allow the rerelease of Cosmetic items that are no longer available, even two years after the initial release.
They would have to be available only through the means of an extensive and costly grind which would still hold value to them.
It would only devalue many of the EBay scalpers markets which currently sell Ferryman Set Codes for up to $1000.
The players who would argue that you had to be there or buy it to earn it originally would still be able to hold the argument that they have had these items since their original release up to 2 years ago.
It would give players who are willing to put in the time, effort and currency a second chance to finish Sets that are not completed for them or they missed out on entirely.
Another example is the Wandering Reaper cosmetics, I had previously earned the Shipwreck Reapers items however I had missed the other Sails & Hull due to my friend informing me that the cosmetics were the exact same.
Once you complete a monthly updates commendations & rewards the only thing left to grind for is commendations that simply reward titles and nothing else.
This would provide another option to grind for and spend currency on.
Certain items were never removed and yet others have been entirely.
Case in point the only earnable Scar set is still available to earn to this day (Forsaken Scar set) and yet the Hungering Deep & Cursed sails scar sets have been removed.
Only a few cosmetics should not follow this I believe since they were only available to a very select few, such as the (Overachiever Sails {even though I was so close} , Loot&Lore Sails, Dev Sails, Rising Sun Sails & Golden Banana Sails).
This is a topic that requires great finesse in order to not upset those who have most if not all of the previous cosmetics (don’t make them twitch drops or easy event rewards - example - Merricks Drum) as well as provide a means for late players who have put in more time and effort than those before them.
TLDR - Make previous Cosmetics earnable through extreme Grind & Currency.