All I know is the last two weeks of running mythic IEs has been awful for me. Not one vanity drop at all.
Wow. It sounds like you really need to take a step back. Doubloons drops are as common as they ever were. It’s uncommon that I don’t get a bag of them after every expedition. You are just expecting too much.
The pets that drop are not useless. People collect them, sell them on the AH, give them as gifts, and (gasp) actually fight pet battles with them. Maybe that’s not your thing, and that’s okay. Don’t assume that everyone’s thing is the same as yours.
If you really have been doing the islands for a while, then you must have noticed the ever-uncreasing difficulty from week to week. The AI is tougher, cheats more, and is more aggressive. The mobs special attacks hit harder. The mobs have more health, and the islands themselves have tricks up their sleeves. Expecting to not die when you pull a group of mobs because it’s only on heroic is foolhardy, and overconfident. Never underestimate your enemy.
The islands also drop transmog items, some of them quite valuable. Some, not so much.
Lastly the mounts do drop. After a couple thousand heroics, mythics, and pvp islands I’ve got all but one pet, and have received two of the mounts. The dumbest, and ugliest ones, of course, but that’s just my luck.
If you go into the islands with an attitude of entitlement, and think you’re too powerful to die. Well, you’re going to be disappointed.
How can you find out how many IEs you e done?