Diamond Miner like item should be a thing in every gacha game

I've been playing gacha games for a long time now and I have to say that the diamond miner is a brilliant idea. Just think about it, for the price of a new 3DS retail game, you get a reliable source of additional premium currency. Besides the obvious advantages for the customer, the game creator would also benefit from this system, namely that the customers are more motivated to play the game for a longer time and thus possibly spending more money.

Thoughts?