Much like the goal of Pakistan is to one day destroy India and hurl its flag on Red Fort, the goal of the US administration is to prevent proliferation of nuclear weapons.
The main aim of this deal is to cap India's nuclear program not enhance it. This is how this deal have been sold to the Congress else it will not have any support. The deal will enable US to establish people to people contact with India's nuclear scientists which will enable them an opportunity to develop HUMINT a.k.a spies in the nuclear establishment. Currently the Indian program is cloaked in secrecy and I suppose it must remain that way. We need U235 and plutonium to make bombs and not produce power. I think we have sufficient material for a lot more time in future.
The left sucks on economics ( and I would be happy if they copy Chinese ) but it has taken a decent stand this time. Much like how they stopped our troops from going to Iraq 4 years back.