The Guild is what keeps people playing even when the game gets a bit stale. Creating a good Guild structure is key to Vanguards future. I hated guilds in WoW as you were all forced to level at the same rate or lose contact and a level one joining a guild of level 40's was pointless.
A good healthy Guild has a broad range of levels races and characters and that goes for your game characters as well
I used to love logging into Horizons and get my level 10 char invited to join a group of Guildies heading into the wastelands led by a couple of level 100's.
there was about 150 in my guild and we all played together.. This is how it should be.