After seeing these accounts in action, the premium loot bonus is completely unbalanced. A much lower cost and lower benefit would have been better for the game in the long term.
The flood of new loot/resources means that there is no scarcity with resources and de-values the work of building up your island and drives resource prices down. We lose the balance that this game had and made it attractive. When there's no perceived value in resources, or the efforts to attain them, then nobody is willing to expend any effort.
The premium also creates a major disparity between players. Casual players are unable to gain value using premium. You need to be acquiring loot from several high-level adventures every day in order to justify the cost of the premium. That means putting in a lot of time online at the game, and a lot of players are not interested in the higher level of commitment. Demand for lootspots from premium accounts is so high that Non-premium accounts are basically driven completely out of the Lootspot market because there is no longer any profit in it. The Non-Premium accounts become adventure-slaves for the premium accounts -- spending their time doing the dirty work while the premium accounts get rich off their efforts.
I like the idea of increased gem demand, and I understand how the recurring revenue is attractive to the developers. But when you start messing with the game and it becomes badly unbalanced and unsustainable -- then you end up with something that's not worth the players' time.