As a non-bitcoin user, it seems to me that the value of the system as a medium of anonymous transaction is mostly irrelevant to the current price. As long as its stable enough for that, the only "problem" with the bitcoin price crashing is for speculators...
It isn't stable enough for that. The price has moved +30% within a few hours [1]. That's easily short enough to cause problems for both merchants and consumers. For consumers, they risk the bitcoin price falling after they've purchased bitcoins, but before they've purchased something with them. And even if you succeed in buying something with your bitcoins before the price has gone up in bitcoin terms, the store owner might lose if he doesn't cash out the bitcoins he has earned before the price falls.
There are plenty of risks to non-speculators. But in fact, the speculators, by providing liquidity, help the non-speculators enter and exit a bitcoin position quickly and with minimal losses (tight spread). Were it not for the speculators, services like Bitpay couldn't exist. Speculators continuously incur risk holding bitcoins, and market makers literally take on the risk of holding bitcoins, transferring this risk away from the consumer and merchant (who can quickly enter and exit the bitcoin market because there are constantly people willing to sell and buy bitcoins (among them market makers and price speculators)).
TL;DR: Have you thanked your local speculator lately?
Bitcoin is extremely volatile. As sibling said, it's even volatile enough to change price significantly in the time it takes for a transaction to be validated and move through the system!
Currently the only reasonable way to deal with this issue is to pay through an exchange (where they can validate internally), which isn't in itself a problem, but then it won't be anonymous (unless your exchange is participating in money laundering, they are legally obliged to verify your identity)
