The objections revolved around sense of community and being able to police bad behavior by randoms. Those objections vanish in ranked if ranked teams are restricted to 8 man premades. Even for normal wz these objections can still be surmounted however. Simply restrict team formation to be of players from the same server.
In reality I don't think BW view the "community" aspect as a hurdle to x-server anymore. Now they are simply stumped by the technical problems arising from the Hero engine.
This is a strong possibility.
On the other hand, PvP is 1 of the end-game areas; it'd be worth to put some people on some coding for an additional amount of time to effect such a change.