It’s an easy reflex to express outrage when a former leader in an industry is appointed to regulate that industry. Of course, we say, they’ll look after there own (i.e. other executives) at the cost of regular folk. I don’t think that such natural distrust is necessarily a bad thing, because it’s clear that there’s the potential for a conflict of interest, but if the person is chosen well then their experience can be a huge help in keeping an industry well-ordered and prosperous.
On the other hand, if you use a recess appointment to fill the role of the Mine Safety and Health Administration, and the person you appoint had overseen an injury rate twice the national average during his tenure in management, then you should employ every reflex at your disposal, because you’re looking at two incompetent managers, not just one.