Every day you leave the RG active, the Aurora ’s hull continues to degrade aesthetically (more fires, more collapsed walkways). Furthermore, you cannot build a Seamoth or Prawn Suit dock near the Aurora without the vehicle taking damage. And critically, you cannot complete the main story without fixing the RG, as the Captain’s Cabin (which contains the rocket blueprints) is locked behind the radiation zone.
Contrary to a common myth, you do not need to "repair" the Radiation Generator. You cannot. The RG mechanics are resolved through the Aurora ’s drive core. subnautica rg mechanics