I wrote that archetype, and one design goal was to make the archetype different from the Champion of Irori prestige class. If it were too similar it might cheapen the prestige class. If it readily provided the prerequisites, it would make transitioning into the prestige class too much of a no-brainer. Instead, the archetype is something unique that can stand on its own and is an attractive option to take from 1st level all the way to 20th.
I'm very happy with how the archetype turned out.
It's very cool, I'm definitely not complaining. I just had sort of a "Huh, that wasn't what I expected, I wonder why they went that way" reaction.
Besides, in hindsight, it completely works that there would be multiple 'paths' for a holy champion of Irori to take towards enlightenment.