Dear Sam.
I understand your point and agree that "virtual" implies something that is not real and actually it is very real.
The issue seems to be what the US decides is a currency as defined under their laws (which they change to suit themselves when they wish) and what others , particularly those in this community and hopefully the majority of the population eventually, decide to accept as currency .
If a group of people agree that this is a currency then it certainly is for them and they can use it as such whatever the law may say. Unfortunately they cannot call upon the laws of the USA to enforce anything should things go wrong. As long as they are aware and accept that then everything is fine.
When there are enough people using it the law will probably change to recognize it as a currency with all the protection that the law currently provides for the US dollar but it will be regulated. However, I thought that regulation is what the concept of bitcoin was trying to avoid and if that is the case then it will always be outside the law because anything (of size) they cant regulate they will surely make illegal. If it is destined to be outside the law then mass adoption in everyday commerce will probably be very difficult if not impossible.
I would suggest that some type of compromise will be needed in order to further the cause of mass adoption and would be happy to hear others opinions on this as it is critical to how fast and how big Bitcoin can grow.