(Below is entirely opinion).
At their core, Island expeditions are both too mechanically simple and needlessly grindy.
Basically the experience can be described as going to one of three pre selected islands and farm dungeon trash until you fill a bar - and occasionally gank a few opposite faction members.
No matter what the rewards are, the number tuning, or the randomness of the species that show up on the islands, as long as this isn’t addressed, IE’s are going to be more or less a chore to complete.
Visually, Island Expeditions are boring. While the islands themselves are interesting, there is very little feedback with the environment at large. Capture an Azerite drill? Looks almost identical if you were assaulting the drill. Ship about to set sail? No difference.
While random events do impact visually, the player’s actions on the game have little feedback. In Battlegrounds, when a point is captured, there is significant amount of work put in to show that “The Alliance holds this point, the Horde holds that” which ultimately makes a player feel as if their actions on the battlefield are impacting something.
Translating this into Island Expeditions, visually spruce things up a bit. Capture a drill? Plant a flag. An important building? Drape your factions colors over. Ship about to set sail? Get some sailors running across the deck looking busy. Maybe put some glowing boxes of Azerite on the deck. As of now, IE’s almost have a sterile feel to them. Putting in some visual flare that gives the player some sense of accomplishment will go a long way.
Another issue I have with them is fundamentally the gameplay is Click X chunks, kill X trash, gank Hordies. This really isn’t all that interesting, as its pretty much just doing Champions of Azeroth World Quests with Warmode on…but in an instance.
Objectives would be a phenomenal addition, even if they aren’t “Required” to win. Maybe randomize them - such as one expedition having a capture able stables that increases mount speed, a smithy that increases your armor, a mage tower that increases damage…really any sort of objective that is tempting for both factions to try and take - but are not required to win, so the choice to push X or keep gathering is still available. (Objective idea that I’d like to see is raiding the other faction’s ship to steal Azerite. Maybe those azerite boxes I mentioned earlier can be made off with?)
The rewards structure is still annoying to me, as ultimately the vendor added is fairly…pointless. It didn’t address the problem that people were asking for a vendor for - namely that the rewards on the IE needed something to target them outside of pure RNG on top of RNG. Likewise, the drops aren’t really worth the effort outside of cosmetic appeal. Leveling an alt through IE’s is needlessly punishing, as you will have basically no gear by the time you hit 120 - even if it dropped 320 blue’s on a semi-consistent level (equal to a Heroic Dungeon) would be a breath of fresh air.
But…as of now, IE’s are pretty much just clicking chunks and clearing wave after wave of trash mobs. Something has to change mechanically for them to be really fun. I want to like IE’s…but as of now, they are just terrible. I feel like all it would take is some minor (Okay…X.X.5 level of changes) to turn IE’s from a generally bad experience to something truly special.