@roostusa You missed the hungering deep event which was a few hours of fun. At this moment the megalodon from that event isn't in the game but I assume sometime this month they are gona put it back in as a wild animal you run into sometimes.
The skeleton throne event is going on now where you sit in ten thrones hidden in the world 5 with someone from another crew 5 by yourself and you get a new currency bilge rat money. Until I think 6/26/18 you can buy a cool skeleton hat/coat/dress cosmetics with this currency. They plan to make more with this from the 'weekly events'.
This event is going for two weeks so I'm not sure about them sticking to the weekly events unless they are gona over lap them which I think would be great. Why can't the guy give more than one mission at a time? You can use this currency to boost a faction about a quarter of a level or to buy gold as well.
They have also added a lot of cosmetics to buy at the store in the form of clothing and a few ship hulls/sails. They also added a drum instrument, a new shanty, and a loud speaker for talking to random people at a long distance. They added flags to put on top of your ship as a mini decoration. You can alter your tattoos and scars a bit as well now.
All that said, if you left that fast, I suggest you wait until at least cursed sails dlc comes out in July sometime. It adds a new 3 man ship type and another new threat the skeleton ships to fight off. Also adds new cursed canonballs that should make weird things happen to the ship/crew it strikes. And that is just what we know of it. So that would be the time to come back I think OR if you are patient/don't care about time limited campaign rewards wait til september.
I assume at that time we will have boat loads of new cosmetics, the megalodon, a new area to explore that has volcanos, rowboats, maybe a couple instruments, hopefully a few new voyages to do or voyage alternatives to gain experience.