Guild Wars 2

Some missions require good timing and/or coordination.
As it is now, anybody can just come and mess with your organization.

Please, allow us to choose whether to open the mission to outsiders or to instance it for guild members only.

assuming whoever sets off tequatl has over 100+ members online and willing to go ad fight – i prefer it not to be instanced

Last I checked, Tequatl isn’t a guild mission. A guild mission is a bounty or race I thought.

Guild missions were intended to take place in the open world, in order to draw players together.

It must be inviting for other players to join in on the rush/puzzle/bounty for fun, and maybe make new friends. ArenaNet probably even thought this could be a good way for guilds to recruit new members.