The devs left it in because there was likely disagreement at the company over whether or not it should be allowed.
Keep in mind bomb mining wasn’t possible until only 3-4 months ago, they had no idea how it would affect the economy.
Once they started seein’ some of the vets on here who constantly defend bomb mining run around with 7meter AOE bombs cleanin’ up entire planets then charging an arm and a leg for diamonds in shops, they realized the mistake.
Edit
The grind for gems, and progression is broken, and I talk about’it in my post, please visit it and respond with your thoughts, Mining Progression, New Hammers, T4 Worlds, a solution