As a bunch of people have been talking about recently, including myself. E is not used for much, especially because the in game costs for anything that uses e, are quite massive. Now u put this into relation to the USD amount, and why would a player feel incentivized to buy gear / items from the depot for any reason other then the usual stuff players already buy. Even recovering accessories off armor is a steep price, which isn't a big problem for the reasons of there needing to be a energy sink in the game, but for the reasons of incentivizing players to spend the paid currency, also incentivizes players to buy more of the paid currency. So my proposal is this.

Change the USD - Energy price, Give us more energy for the same dollar value, there will be 0 loss on the income of energy sales, if anything there will be a increase, as mentioned more players will actively be incentivized and feel less crappy about spending energy on various things in the depot. Including weapons / gear. It hurts nobody but the player-base for it to be as low as it is, it just should not be.

As it currently stands any piece of 5 star gear is 3500 energy, and 3500 is 10 dollars. Heat amplifiers are a massive red flag in my opinion, as for a 30 day booster it is 5k energy. or 15$. Just to heat your gear a little bit faster?

Sprite gear is a section that could see some love, and thus causing more energy purchases as well. Most sprite skins in the game are extremely rare as they only came from a box released AGES ago that never reran. Players LOVE fashion in this game, and I think their sprites deserve some of that fashionesta love.
Most players don't get a chance to get any of the sprite skins outside of the two that are craft-able threw in game events, so providing a way for them to be obtainable threw recurring sales of the sprite skins already available in game, or new ones the team could make in 5 minutes and throw up on the shop!

A new decoration section could be added to go along with my (not to self promote) Player housing-like idea of player specific mission lobbys, with the ready room being move to here to display each knights decorations as they log in and to others when they host a lobby. But also with the current guild hall system and guilds getting a massive resurgence of active players taking them in.
This section could include certain decorations that are always on sale, and some that change out whenever the team sees fit.

This is something I feel most of the players would accept openly and have 0 complaints with, and from a developer standpoint, does not hurt the company at all, if anything generates more income. So therefore I along with many others see this as an entirely win-win situation, that will not ultimately fix the growing economic issue within SK, but without a doubt aid it drastically.