200,000 refugees on the whole over the next decade, not all or even a large percentage of them Syrian, to clarify, though it doesn't detract from your question, which is a rather loaded one.
First, it's important to understand that the Obama administration's acceptance of Middle East refugees is largely a shot at the prior administration's military efforts having been successful at destabilizing the region. So, in keeping with the "you broke it you buy it" ideology of foreign affairs and refugee intervention that saw 750,000 Vietnamese refugees to the U.S. after we left Vietnam, the administration's obvious move is to welcome new refugees. It's two-fold, in that they get to remind people that they believe this is all GWB's fault and look humanitarian while doing it. Cleaning up the mess of the prior administration has largely been the current regime's selling point, and this helps them ride that line.
Additionally, refugees are, far more often than not, normal people displaced by turmoil. Middle Eastern infrastructure simply isn't capable of handling the influx and it is a major burden on already finite resources. In taking in refugees you get a big plus mark in the foreign affairs column by reducing strain on Jordan and Iraq and the EU nations lending a hand.
Furthermore, because it's the right thing to do, regardless of what those around you seem to think. If you think these attacks were carried out or even aided by France assisting refugees, you're letting xenophobia get the best of you. Far as we can tell, these attacks were orchestrated by three French citizens. As in, they already lived there. Did they perhaps prey on refugees who were ironically being harbored by a nation aiding in the slaughtering and occupation of their homelands? Sure. But this would've, no doubt, happened regardless of whether they took in refugees. As sad as these attacks were, I think the saddest part is that they lend to the notion that humanitarian efforts fall second to our fear of terrorism. There are two million displaced Syrian citizens; fathers, mothers, children, who often die en route to refuge and, if they make it, find themselves in deplorable conditions because they're being taken in by nations far less wealthy than ours. Newsflash: hundreds of thousands of people who hate America, share radical and destructive ideas about Western culture, and genuinely want you dead the moment they wake up each day, they already live here. Does that keep you from leaving the house or helping strangers in need? Nah. So why should attacks on French soil drive us to turning a blind eye to the aftermath of a mess we created? The question we should be asking is why Syrians, when millions of Africans are displaced annually due to military conflict, a question I think we can all answer.
Lastly and significantly less importantly, because refugee groups tend to be treasure troves of untapped talent, so for all we know we're letting the next dozen great scientists in. 40% of America's Fortune 500 was started by immigrants, food for thought.