The exchanges are actually on a weired situation, most of them are aware of the SEC and the different US regulations, remember what recently happened to BTC-E, even if it haven't started from the SEC at least, they reached them outside borders.
I believe this is why Bitfinex is now refusing US customers. There are more regulations every day, different countries are trying or starting to regulate bitcoin and cryptocurrencies markets, this is a serious limitation for exchange listing. Even the ethereum tokens are under regulation threat.
Thats the reason why we need a decentralized exchanges.
We are in the wonderful situation now that we have the right tools to counter restrictive policies. Thanks to Nakamoto, we can circumvent most of the stuff that is limiting our freedom in a reasonable way. I am not saying we should go nuts, but policy makers will have to recognize sooner or later that the world changed. And the more they restrict us from actually doing quite normal things, the more we will push with our financial means to achieve the opposite of what they try to achieve. I like crypto guys. I am all for tax, it is important to keep public infrastructure alive. But I can't see the reason why the US should crack down so hard on ICOs. There need to be rules, but they have to be in line with the present and the future, not the past.