Isn't wide acceptance of bitcoins based on some form of backing (not necessarily assets) but at least governmental... which raises at least the following 2 issues:
1. Even though there may be a secondary market insured by agents/brokers. In case of busts & credit crunches, those may/will not be able to support it, hence the trust in this market could erode quickly & holders of bitcoins May be caught with their pants down !!
2. not regulated by any agency, hence it can be a good medium for fraud, tempering, laundering or speculation... who will protect the holders?