These sound similar to Guild Wars 2 "Events". Some people have mentioned that these would be a great addition to the game. More group "events" like Anchors that occur at random zones would be a lot of fun and may be easy to program/implement.
I have played RIFT and GW2. I kinda ride the MMO merry go round. But I liked the instant adventures because you were ported to an area. Auto grouped. and quested for XP/loot. When one quest was done you were assigned another in that area.