Yah, it says it at the beginning of the chapter, even though several salient abilities are useful without a divine rank as Dante & Vergil said.
It seems to me as the logical progression, you have forsworn any items and therefore become closer to being divine, you gain perfection at 20th, quasi divinity at 30th and Divinity (rank 1) at 40th, to me that establishes the actual power level of more powerful gods. (Level = rank x 10 +30)
And If they are 40th they should be pretty darn close if not all ready, plus I do believe there are several Epic Destiny's that do similar things, maybe to a lesser extent as there is really nothing written for 31+ level of play.
I have had the same feeling but I did not want to rewrite Vaynor's and/or Drolyts original idea, it has become the standard VoP on these boards and I don't want to mess with it.
I would most likely change it to a standard increase like the Deflection bonus or make it equal to your Constitution Modifier.