I have seen several players using the Grouping panel for guild recruiting, and I have seen some players complain about it. We do have the forums to try and recruit for guilds, but you yourself have said that only a small % of people use the forums. So I have a compromise. Would it be possible to add a new tab to the in-game social page, for the sole purpose of guild recruitment? This would clear up the grouping panel (which seems to be the biggest complaint) and still allow guilds to reach the largest possible target market.
What I am seeing is a new tab called something like recruiting (I am sure that your clever writers could come up with something better), where an officer/leader could post something similar to posting for a group. It would still have a notes section, that way the poster could give a little info about their guild. When a possible recruit clicks on the posting, it informs the poster that Player A would like to join your guild. Then the two players could start a conversation in which ever method they choose to see if they are a right fit for each other, or if they choose the poster could just simply send Player A a guild invite.
I see something like this as a win-win situation. It still allows those guilds that wish to recruit in game a way to do so; while clearing up the group panel for those that are already in a guild or just looking to join a group.