Perhaps they would have had to dump fuel to "land ASAP" anyway, so why not just turn around,fly back to CDG and land normally rather than dumping fuel all over Europe, and landing at some remote airport where the plane isn't going to get fixed in a hurry....
At the point where the decision not to continue was taken, was the aircraft likely to be still above maximum landing weight, and if so, how long would it take to dump enough fuel to get below MLW? How long to burn enough fuel through three engines?
If you need to spend the time up there, and there are no indications of imminent failure of any of the other engines, then making a straight line for home seems a much better option than circling over the middle of nowhere, or landing landing hundreds of miles from support. And of course in the last 90 minutes or so before Paris, places like Copenhagen, Amsterdam and Brussels would not be far off track if anything else did go wrong.