I've been reading a lot of posts of players complaining about the energy system and suggesting that there be a fixed price. This is not the answer. If the price was fixed at say, 4k or 3k crowns, you would just complain about that being too pricey as well. The root of the problem is that you don't have enough energy to continue playing. that's why my suggestion is this:
Keep the main focus on delving deeper into the clockworks but allow for those who don't buy CE and even for those who do (Like me) to explore the surface of Cradle. Make 1 - 5 star areas for all different players. Create instanced areas for players to explore on the surface of Cradle that require no energy but still allow you to collect crowns and maybe a few materials. This will at least allow players to continue having fun while earning enough crowns to buy the CE required to go into the clockworks.
Really my suggestion is to make something else for players to do that doesn't require energy to keep them interested in the game. Open up a PvP arena for all I care. Let them kill each other and they will come back for more.
I realize this is much easier said than done but I'm going to keep donating and maybe my suggestion will become (virtual) reality.
You know what would be even more fun? Make the surface a persistent world with fully enabled PvP where players can go kill each other as much as they want and when a player dies they drop all the crowns and heat they accumulated since the last time they have been in haven. People might complain that players would just farm on the surface rather than in dungeons but the players who would dominate here would be end game players who don't buy CE anyways. Newer players would have extra incentive to buy CE and quickly work their way up to take revenge on the experienced player who killed them before.