I don't heal unless someone can get the full effect of a spell and only ever otherwise start casting before a big incoming hit, so I assume the threat issue isn't mine.
I also always run to the tank when I do have adds on me, but usually to no avail.
Honestly, it hasn't really been an issue so far, seeing as it's still early in the game and any class can tank X amount of mobs indefinitely, but it gets on my nerves.
