In this circumstance, it's better releasing the game having a skill perhaps not being powerful enough rather than having it be too powerful, so even if they're wrong, it's still the "safer" solution.
Skills for the most part can only be considered overpowered in relation to other skills. If the developers release the game with sub-par skills, it is not a "safer" solution. The sub-par skills boost the relative power of the par skills and you see a lack of customization and increase in cookie-cutter classes. Since it takes precious developing time to develop, generate, and test these skills, developers should only focus on things they can tightly balance, or otherwise leave it out.