Why is Mitt Romney's time at Bain Capital such a target?

Why is Mitt Romney's time at Bain Capital such a target

“During the nearly 15 years that Romney was actively involved in running Bain, a private equity firm that he founded, it owned companies that were pioneers in the practice of shipping work from the United States to overseas call centers and factories making computer components, according to filings with the Securities and Exchange Commission,” the Post reported. “While Bain was not the largest player in the outsourcing field, the private equity firm was involved early on, at a time when the departure of jobs from the United States was beginning to accelerate and new companies were emerging as handmaidens to this outflow of employment.”