I was just levelling up my latest Blood Elf and reading some of the quest text (specifically the one where you find the nelf and dwarf spy) and if I remember correctly the Blood Elves don't 'join' the horde until the end of the quest chain where you go Sylvanas and then Thrall (similar to how Goblins and Worgen don't join their new fsctions till the end of the zone.) and it kinda breaks immersion when you see horde etc running around (yes I remember the forsaken you meet in ghostlands)
And this got me thinking about how much more they could add to all the starter zones if they instanced or phased them to show things like joining the new faction etc and would be a nice way to get people into the lore of their class and would also bring the starter zones up to scratch with the Worgen/Goblin zones.
I know its probably just a pipe dream and we won't see something on this scale added.
Hope I got my point across properly