I read this earlier today and it may answer some of your questions:
http://www.biz.uiowa.edu/class/6f130/lect_06.ppt.
My take on it was that speculators play an incredibly important role in the Forex markets and it seems to me that may be partly why the government is leaving it as unregulated as it is, to provide incentives for increased speculation which gives governments and banks increased liquidity, while most of the risk is assumed by speculators. I may be wrong on that, but that's what I took out of it.
Kali