They should make a sort-of LFG Channel which you only enter when you're actually searching for a group.
For example: when you want to start looking for a group you tick the box at the 'who' tab in the social window. When you do that you'll enter the global LFG-channel. This'll also get people to use that 'who'-LFG "system" a bit more, because I hardly see anyone using it. When I try and search a group I search for people, and as usual I am the only one who is using it.
I think this would help a lot. If you don't want spam, you untick the box of LFG at the 'who' tab and you're free again to live in solitude.