Hypothesis: There are far more players interested in RvR on Destruction than Order.
Expected outcomes: Order scenario queues are trivial, while Destruction scenario queues are lengthy. Open-world RvR will be dominated by Destruction. At lower tiers, when scenarios are the dominant method of gaining renown, Order will have an advantage; they will have more practice in each scenario and RvR generally, along with higher renown rank. Leveling will be faster on Order, if you use scenarios to level. In the long run, Destruction will dominate most servers in tier 4, because they will have more active players in RvR in the open world.
Data point: I spent more than an hour in a queue on Destruction, perhaps two hours, without getting into a scenario. I have never waited five minutes on the Order side. After waiting the one to two hours on Destruction, I switched to order, ran seven to ten scenarios in quick succession, and gained two levels.
Corollary: There may be more people interested in Destruction generally. It is the evil faction, really evil not just Horde, and it is a naturally attractive element to the hardcore PvP population in a game that promotes itself as the PvP alternative to WoW. Carebears are more likely to want to be pretty elves with white lions than heavily scarred goblins with biologically improbably squigs.