I put a lot of time into this, so if you care about this please read and if you agree please share it.
In my opinion, Island Expeditions have the potential to be what Mythic+ was for Legion. PvP Island Expeditions only though, the PvE versions are boring and often times harder because the Blizzard AI is smarter than most actual players. In this post, I'm going to make a list of changes, improvements, weak points, and everything else in between that I feel Island Expeditions need to be more engaging to players and also an audience:
--Closer parity between individual mob difficulty relative to their rewards. A simple example: crabs are harder to kill than crocodiles. The reason for this is that crabs can root you then cast an AoE cone after the root, crocs can only cast an AoE cone and a slow. There is a clear difficulty gap between these two mob types that will lead to crabs always being avoided and crocs always being pulled. The difficulty gap would also be completely fine if crabs gave more points than crocs, but they don't. In my eyes, I consider it boring and shitty game design to be indirectly pigeonholed into only killing certain mob types while other mob types are ignored entirely.
A mob that can combo (root+cleave) should give more points than a mob that can only initiate one piece of that combo (root or cleave). This also works inversely with the mob types that are too easy. My solution would be to make crabs root and crocs cleave, that way they are unique and also have synergy with each other. The reason parity between these mobs is needed is because we don't want the Island Expedition meta to mirror the Diablo 3 Greater Rift meta where you have to fish for the right map and mob types to push the highest rift levels. It should be Island Expeditions not Croc Expeditions.
--Rethink the Doubloon system. This is more of a competitive concern and less of a casual one, but I think being able to go into an Expedition with 40 doubloons and spend them all on tanks (more on those later) and buffs is against the spirit of competition and not a very good system for competitive play. It's not(less) satisfying to win against a team after spending a ton of currency to beat them and it's also not satisfying to lose to a team because they used a ton of currency to beat you.
Doubloons would be a lot more interesting if they were awarded to players after killing rares/rare elites and were exclusive to that specific match. Basically, the resource system we see in a lot of MOBA's. Not only would this level the playing field but it would also make the end of the matches more dynamic and different than the beginning. It could create more points of interest around the map and draw teams together to compete for rares more often.
--Tone down the bullshit items. Yes, it's no coincidence that this post is being made on the same week that the siege engines are available. It's pretty stupid that you can be cc'd and then literally one shot with an item you can buy from a vendor at the start of the match. Even though these items are available to both teams, they create an contrived meta that requires you to either use these items or lose (assuming both teams are similar skill, of course you can beat terrible teams regardless of items). Being stunned and then having a tank drive on top of you and cast an AoE ability that instantly kills your character is not fun.
I'm not saying to remove these items, but many of them with little to no counterplay potential (arcane wand and tanks) should have their effectiveness against players reduced by 75%. This would allow them to still be meaningful in team fights without them being the deciding factor. It would also create a second level of meta gameplay especially around the tanks where teams that used tanks would have to actively protect them and focus more on killing NPC's and less on players. Items should modify and enhance matches, not define them.
--Make arena frames activate when you're in combat with enemy players. This is kind of a simple one that helps visibility and makes it easier for players to see enemy casts and health bars.
--Create more diverse PvE mechanics. Almost all of the PvE mechanics are either front facing cone shockwave abilities, 360 degree AoE abilities, or forward facing lines that deal damage. Maybe this is just because I'm a melee, but it seems like almost all of the mechanics in Expeditions are melee focused and not enough are caster focused. I'd like to see more mechanics that aren't melee focused such as a version of King Deepbeard's (Eye of Azshara sea giant boss) stomp mechanic that puts a danger zone under every player that they have to move out of.
--Create more deterministic rewards. The mounts and pets should be buyable with some sort of currency rather than all of them just being random drops. Giving players something to work towards is more satisfying than giving them a lever for a slot machine. They're also not mutually exclusive, but I'd like to see some sort of way to offset bad luck considering that there are so many rewards you can get from the expeditions.
--A warmode system that allows two 3-man teams to queue against each other without rewards. This would let you make tournaments and allow teams to practice against each other. If Expeditions are ever intended to be a competitive activity, you need a warmode system.
Yes, this was a long read and hopefully you agree with some if not all of my points. As always I'm always up for discussion and debate about them. My main focus is making this feature as successful as it can be and these are my ideas for doing so.