Manned programs haven't accomplished much of anything useful since the Apollo days. Orbiting the earth and servicing an ISS that is for the most part worthless doesn't constitute expanding the boundaries of knowledge.
There was one useful mission astronauts did carry out and that was satellite repair, in particular the Hubble. We can't even do that now with the new orbit restrictions on the shuttle. We're just spinning our wheels in the manned arena. Maybe Burt Rutan can make it work. NASA sure can't.
But it's symptomatic of the whole program. Lack of vision, timidity in the face of the naysayers, fear of trying new and bigger and better things. Those are classic signs of a program in decline and retrenchment.