Ahhhh, I've pondered this one back and forth. On the one hand, it seems unlikely to me that the extra bonus was intentional, seeing as you don't actually get informed of it in the original game. On the other, I do see your point about the pattern of rewards.
I think the extra perks of the paths you mention (and don't forget the Nymph Cloak) derive more from the game's representation of evil as "self-serving" and good as "self-sacrificing" in the trials than from any desire to make evil the more appealing option. It's difficult to design a morality test which doesn't revolve around this distinction. More precisely, it's difficult to conceive a Greed or Selfishness trial which doesn't reward the player for actually being greedy or selfish, but submitting to your wrath against Sarevok does not neccessitate any actual tangible reward.