Cross realm zones:
-Create choke points while questing
-encourage griefing by players camping mobs
-Cause unwanted lag
-Do not cause a sense of community and people still stick with their realms players.
-Make achievements done in the world hard such as netherwing reputation now.
-Make rare spawns such as Time-lost or aoenaxx more impossible then difficult.
-Cause economical crisis as resources will be limited.
-Allow cross realm in the sense if a player from say Stormrage invited a player from Illidan they could interact in the real world and other players on the leaders server would see the illidan player, Same concept but on a much smaller level and allows it as an option not forced.
-Undo the change entirely
-Have resources, spawns and reputation items be realm specific so players on other realms won't see an ore node in the same place as another.
-Change which zones are cross realm at the moment, I don't mind seeing other realms in blades edge or nagrand but when I can't find my servers players in Goldshire thats too much.
These are just my opinions and I'd like to hear what other players think could be done, I don't want complaints just solutions I may have missed.