You're still at the mercy of the volatility of the currency though.
(guess it's cash under the mattress for now ;)
Bitcoins are pseudonymous, rather than anonymous - and worse, every single transaction ever is documented in the blockchain.
The IRS, I'm sure, is quite happy about this complete documentation, and while they haven't gotten around to (ab)using it, I'm sure they will sooner or later.
And I agree that Bitcoin's lack of anonymity is a big problem. However, there are techniques one can use to keep transaction histories private, like using stealth addresses and decentralized, trustless mixing services like dark wallet and coinjoin [1]. Other cryptocurrencies like Darkcoin [2] have built privacy features into their protocol. These solutions are not yet perfect, but again I think they will continue to improve.
Further agree that abuses by the IRS as well as other state agencies will continue. But why make it easier for them? It's only going to get worse in the future if we do nothing.
[1] https://bitdazzle.com/food [2] https://wiki.anoncoin.net/Anonymity_of_cryptocurrencies [3] https://www.darkcoin.io