Leveling dungeons already guarantee a gear drop for your current job at the end of the run. Maybe they could give the dungeon's card/minion/whatever if you already have all of the gear on you. Just apply the same system to level cap dungeons. I get why they'd leave it out of current cap dungeons, they want to keep those roulettes rolling, but there's no reason it couldn't apply to older content.

For alliance raids, bring back the old raid coins and add a vendor that will trade them for gear and loot coffers. You still have to run the raid to get the coins, but at least it would mitigate the loot RNG.