This game simply does not have the player population to encourage a constant stream of micro-transactions. Besides the fact that it's a rather unhealthy system in the first place, new players are going to drop this game as soon as they realize it's not feasible to keep leveling up naturally. Since so many passive stats and access to higher forge levels are tied to level progression, it further gimps low level players and makes them give up on the game.
Additionally, mid level players (myself included) who are used to the previous system and rate of rewards now have less incentive to continue the grind to higher levels, as the pace starts feeling like a snail. I used to play Spacelords all day, even after completing all rewards, because I could at least keep leveling at a healthy rate with decent rewards depending on the mission I selected. But now, I feel discouraged to keep playing this game at all, especially if MercurySteam is trying to "encourage" buying xp boosters.
As for the maxed out players, they desperately need some better form of incentive to keep playing the game. Eventually they'll max out all guns as they like, and sure the gameplay itself is fun, but there's no satisfying reward. With the faction rewards being merged into a single pool, there's less incentive to try out factions/charaters they might not. The purple currency is frankly rather worthless since there's nothing but a couple music boxes. Add more emotes, amusing voice lines they can trigger, cosmetic reskins, the ability to tip the equilibrium in the guild, anything at all.
I absolutely love this game, and I want to see it thrive and do well. However, at the current rate it feels like it's being turned into a meaningless microtransaction pay-to-feasibly-play.