Even in smaller games, guilds play very important role on keeping new players in the game.
Lots of people who try the game out for a few days and then leave do that because socializing and finding friends to play with can be pretty hard. Not everyone is social type of person. Informative and newbie-friendly guilds can help these new players to not to feel alone and encourage them to keep playing the game. This would clearly benefit even the small player base we currently have, and combined with a little bit of advertising could help the community grow.
While AH or other shop systems are also key components of any MMO, I think guild system has rightfully been prioritized a little bit higher. And I'm also sure that AH will get introduced later because there's been so much talk about it, so lets just patiently wait for that.
While this sound really fun in paper I doubt it will be that entertaining in the long run. Player base in this game is so small and pretty much all the PvP'ers are pals with each other so I think it quickly becomes PvP'ers vs other players -activity. And while PvP'ers have big advantage over others ( customized builds, PvP experience etc. ) there's high chance this kind of activity only becomes a farm for PvP'ers to gain "practically free" high tier loot every now and then.
At least this is my point of view. I think this only widens the gap between PvP and PvE folks. If something like this gets introduced in the game I might take part of it a few times for pure excitement but I doubt lonely nubs like myself have any chance teaming up with anyone for activity like this.
If the game lacks rewards for PvP -activities ( There are some discussions about this ) wouldn't it be better just improve valor gain from battlegrounds and add new rewards purchasable by valor points?