If you remember back toward the end of Wrath of the Lich King, Blizzard introduced the now famous Looking for Dungeon feature (LFD) which caused (and still do) quite a commotion.
The core issue was rather simple when you look back on it. Giving player more convenience when it came to finding dungeons groups versus community building on individual servers. On one side of the fence, you have players saying that player convenience is what matters in a world where play time is limited and you don’t want to spend evenings finding people. On the other side you have people saying that forcing grouping on the same servers makes you accountable, thus less likely to be a jerk and builds community in the long run.
For the record I’m on the accountability side of the fence and it seems Bioware agrees with me as Bioware employee Damion Schubert posted yesterday on the forums
… That being said, our design team doesn’t philosophically believe that cross-server Flashpoints are good for the game at this stage in the game’s lifespan. There is huge social pressure to not be a jerk that goes away when the odds that you will never see these people again is high. I’m not saying never – there may come a time in the future where we reevaluate this – but at least in the short-term, we believe this will cause more damage to the community than good.
Reading the whole discussion you get they are looking to add a LFD at some point for “in-server” needs but cross server looks to be dead so far. Curious to see how this will evolve.