It seems to me that when you add Attributes to Heroes, you're moving from "choices" to "strategic decisions". The word that stands out for me in the description of Attributes is "personalize".
I'm thinking that without Attributes, you can assume that a Paladin is a Paladin is a Paladin, or a Dragoon is a Dragoon is a ... etc. Ie, known quantities. But when you add Attributes, not only does it make the game play more interesting for the player using them, it also would make it more challenging (and thus interesting) for their opponents.
All assumptions on my part.
I'm curious, you see, because this isn't the first time I've seen "drop attributes" in the same post as "improve the PvP". I'm not seeing the link.