The 'nation state' model was put on notice the very minute we realized that technologies like travel and telecoms would become fast, cheap and universal. Things like commercial jet airliners and the internet are going to kill national sovereignty, and if any country in particular doesn't cooperate with the trend towards globalization, it will be left behind like some weird, self-excluded hermit.
Just ponder it for a minute. It's very strange that we can instantaneously text/Skype/message each other on this forum, but at the same time we cannot visit each other, sell our belongings to one another, or do anything much more than talk to each other, without jumping through hoops of immigration, trade and regulatory laws set by our respective countries'. All of those artificial barriers between us are arbitrary and quite unsustainable in light of what our technology does for us. In a future where we all can make friends, fall in love, or go into business with someone halfway across the world, at the exact same speed as you could do with someone in the same room, it is moronic to believe that things like TTP/TTIP, international commerce and governance are preventable.
President Obama and our countries' leaderships realize this. The world is flattening and if their country purposely chooses not to participate in it, their countries' objectives and preferences of where they'll stand in this transition to a global community will be completely disregarded. Which is why global leaders are in favor of TPP/TTIP. If they oppose it, their economies will be run over by every other country that does enter into the trade agreement.