To me, the #1 thing that is wrong with wow right now is the LFGuild tool/server transfers. If you try to look for a guild in game, you'll either see the guilds that are recruiting for heroic raiding on trade chat/casual guilds that don't raid/mediocre guilds "looking for exceptional players". To the new person, none of those guilds suit them if they're looking at starting raiding outside of just LFR. Using the ingame LFG is a mess, since its a jumble of guilds and no one responds to any of the ingame applications since both parties have to be online.
As for transfers, paying $25-$55 to join a raiding guild if you do find one is a cost that a lot of people don't want to swallow, especially if they do have alts. I think an effort should be made so that the dead servers are slightly more populated, (think medium pop level in bc/wrath) and make a working in game tool so that people don't have to wade through trade chat or MMO-Champion/battle.net guild recruitment forums to find a raiding guild.
If people were able to view raiding guilds available on their server, (or on another server if they so choose) and filter by times that would suit their schedule and see what item level and/or experience is required with an application form built in, I think you would see a higher influx into raiding.