I believe energy gates are a thing of the past now, with mist energy gone from the game. They cost 3 energy and are not designed to give you more than take from you. With a rare exception when they give you an item. But that exception has happened, like, once in 3 years I played SK. Once I received a 4* item from a treasure box, but not from a locked gate treasure box. The best items I've gotten from locked boxes were tokens, like primal token.
I offer not to simply remove the gates, but to replace them with sealed gates. Once seal is broken, it summons enemies, and defeating those enemies finally opens the gate. These few enemies drop nothing other than hearts, and the gate should have a monster or seal sign on it.
Danger rooms should also be free to enter, and have a warning that fighting in a danger room is hard, and purely optional, should mention the fact that after entering there is no way back until you complete it.
Reasoning: in the past 3 energy wasn't much as you could use mist. Now, with mist removed, you are forced to spend real energy on opening those gates that almost guarantee no reasonable payout.
Added
Please also remove activate-able mecha knights and turrets in jelly farm lands. Requested by Juances.
And mecha knights. And that turret on jelly farms.