The content finder seems to have PUG in mind more than organized groups. If you're running something with your LS, Free Company or friends, you have no use for the content finder, thus you all can just meet up at the proper location much like you do now.

Now, for the rest of the Open World stuff:

Couldn't we have two versions of every dungeon? Take The Thousand Maws of Toto-Rak. What if you had the mission version which you have to enter an instance for, then you have a larger, deeper, free roaming version that doesn't require an instance and that everyone can explore in?