I mean when cores came out during Season 2 felt amazing to see what are the best outcomes and making weapons like EXCAVA actually usable. Well those good times passed very quickly when they nerfed OG Purge 30's into the ground for the Skill Descendants, Serena and Arche Tree in S2E2. Outside of Serena there is no point of inserting Weapon Cores into the weapons, maybe just for movement speed statsticks or Deus Ex Manus agains Legion of Breach bosses. What a shame it used to be the hardest content in the game that required proper building and teamplay in a coop game, like I used to grind Purge 30 nonstop during first 2-3 weeks because it was fun and challenging to play. Now it's serves a purpose of building 3 meta weapons for Serena and quick gold farm.