As I don't play any longer (account runs out the 26th), I don't feel I have much of a say in what happens, but here goes. I don't think it's right for us to up and suddenly abandon the lower levels. You might consider them noobs, unworthy of any attention from the higher levels whatsoever, but what is the point of a guild? In my opinion, a guild in any mmo is there to help each other.
I don't think anything good can come from casting the lower levels out of the main guild. Many people join guilds for friends, and if those friends are willing to kick them out of the main guild because of a level, what does that friendship mean? I can remember in Star Wars: Galaxies when my guild started a guild war with another guild, we took the crafters out of the guild so they wouldn't get hurt. Even though we explained why, many of them didn't come back to the guild when the war was over. Will those low level members even want to stay in the guild after we betray their trust once?