This is another illusion of choice issue. Tam Tara used to be longer and had optional bosses and branching paths in beta. But people didn't care about them and just went straight to the end, so they shortened it and made dungeons more linear. And even if it was branching paths to reach the boss, only a handful of people would get to enjoy the mystery, as once it had been explored everyone would know the best route to take and there would just be animosity towards new people who want to complete their map.