Wanting a 5k - 8k populatin server at start is just madness. The population is slowly rising because people know it's ok to get 2-3 weeks after the start to have the chance to do the quests in a decent time. What's funny in camping 1 hour the starting area scorpions to complete a 100 exp quest? At the moment the barrens are a dead zone, there are so many people that a mob die at the moment he spawn, with 5-6 people camping (Go see thorn hill or the forgotten pool). And we are almost 1 week after start with a server population of 2.5k... with 5k population you spend a week just to get out of the starting area!! Great fun eh?
There is a reason if Blizzard had 2.5k cap servers as I read in this thread.
