Player progression and new player experience are too important to be left to the whims of the energy market. I suggest a two prong approach:
-Make Orbs, Crystals, and sparks of life purchasable with crowns from the supply depot. This allows you to more directly control the new player experience, and allows you to decide things like “how many jelly king runs should an upgrade to 4* gear cost?”
-Make energy useful again with constant, automated rotating cosmetic supply depot sales. There are many items, like basic color tailed helms or other color raider horns, that ran once on the supply depot and never again. These items are effectively unavailable to any new player who joins and sees they have missed years worth of supply depot sales. Energy can find its place as the premium currency for buying cosmetics, something that will be familiar to many people.
While I think the game could do with a more newcomer-friendly progression, I also think it's beneficial for the game's income to make energy purchases the "fast" option to get new gear. I play a lot of Warframe, where supposedly a lot of their income is earned thanks to similar forms of gear-progression options for players who want something now.
While I'm very wary of games getting too greedy with microtransactions, some of these models feel passable for a free-to-play game. The only issue is, as stated, Spiral Knights could use more consistent ways for players to obtain these much-needed items, as their rarity can be demotivating at this moment.
There has been another suggestion here to make daily danger missions award an extra once-a-day loot pool similar to forge boxes. I think this would be a much nicer solution while also preserving the energy price of these items. Players just need to be able to get the correct orbs & crystals they actually need.
I like the other idea, though. I am always hoping the developers will offer more ways to directly purchase cosmetics with energy. I detest gambling on lootboxes and have instead bought various items when they've been for sale for energy, and I'm sure many players would like to do so as well. I also agree that it would be best if newer players do not have to be dismayed at the knowledge of cosmetics they missed from past releases. Item availability is great for preventing FOMO and encouraging new players to become staying customers.