Guild are currently not having much "guild related content" and it is hard to gain prestige as a guild.
It would motivate Guilds to work together to get that Building and earn the prestige. Later on it could be used for Guildwars or stuff like that.
Let guilds have the possibility to earn and place an enclave like the one on Yavin (decorate it etc)
Idea: Just like on Yavin for the Jedi it would be cool to have the building for guilds "placable" on planets / cities.