Just a thought about an use for Eridium, add some Manufacturer specific Vending Machines throughout the game with high-end weapons for Eridium. Maybe one per brand plus one for shields.
I think Earl’s quality level is okay, but when you consider only a handful of items get good rolls per visit and divide that by the number of brands, weapon types, and anointments, it’s very rare to get something useful. Having specialized stores could be a more viable way of dumping Eridium and getting high-quality items.
I know there would be worries about shifting focus to farming Eridium, but in my experience in the time it takes to farm enough Eridium to buy on Earl gun you can get a dozen purples, so it would be a complement to regular farming, not unlike the Manufacturer email every 100 kills.