US regulators act from an excess of caution, primarily as a result of the anti-money laundering regime that was instituted after 9/11. Of course, there are some legitimate concerns that anonymous money can be used for destructive purposes -- there is no debate about that. However, blockchain and programmable money are a fundamentally new technology, in which the states may fall behind. During the internet bubble, USA was quick to embrace the change. For blockchain, it seems that the American adoption of this new technology is somewhat impeded by a legal system that is designed for security above all else, which is regrettable, but also an opportunity for non-US startups to assume leadership.
It is not just the regulators who are extra cautious. It is the fund raisers who don't want to get entangled with the US regulators and incur high compliance costs. I don't blame them - there are enough people in other countries who are ready to subscribe to ICOs.
You are right. Rather than face legal challenge later on, why not just concentrate on markets aside from USA. There are indeed enough investors outside of USA, who can launch and fund a project. Unless of course, SEC would soon issue a legal framework to work with, then it is not worth including USA in any ICO issuance. The government of USA is very much protective of its own citizens and that is something we all understand, anyway.