At launch, the ends of class stories (specifically the Inquisitor and Warrior) required players to return to Korriban to fight enemies at level 50. Since then, there has been an implemented system where the level cap is scaled down for lower level planets like Korriban. I think it would provide a more rewarding fight if level caps such as the level 12 cap on starter planets were removed when inside the phases for class story. I know it isn't impossible, during the rakghoul event, the tunnels are level 70 location on a world with a level capped around 32.
I remember the fight with Darth Thanaton at the end of the Sith Inquisitor story at launch, it was perhaps one of the most satisfying fights in the game at the time since it was difficult and Thanaton was an even match for you. I think it would be nice for this to return to the game in a future update.