If you aren't looking at Arena and Gauntlet, sure, Moonchild isn't an issue because you won't encounter him anywhere. However, there are a few issues on that end as well. Moonchild's design has affected how the devs have been actively changing the game as a whole. For instance, The Alchemist's Awakened passive. This ability is solely balanced around the idea of countering characters like Moonchild; disabling Labyrinth talismans and inflicting passive disable. Rather than have interesting mechanics similar to Oni Eddie's Empowered sword, we got something that is very niche in design. True, talisman disable is really interesting, but it's still very specific in its uses. The devs have seemingly focused away from actually interesting new things in the game in order to fix the problem that is Moonchild. His release has caused a rift across the entire game. In addition, there are characters that are better for farming than Moonchild if you really need him to get through frontier dungeons.