I think they had to bring an end to the Rousseau arc at this point - although the writers strike possible hastened their hand by a few episodes.
Now that she's got Alex back, most of her mystery lies in her past. I think Ben and the Others..and possibly Widmore and Dharma flashbacks will be able to tell her story.
Shame she's gone in many respects, but they de-robed the rogue and made her all domesticated like..before long they would've had her cooking taco's on a thursday and attending Alex' recitals, or whatever..
Keep Rousseau rural or remove her from the show - that's what I say
