Precisely. Bitcoin's main use is as a vessel of value transfer. The important thing however is not the vessel, but the cargo. Otherwise there are dozens of Shit-Coins that have copied Bitcoin's concept and improved upon it in various ways, not least of all making it more streamline. In short, if the vessel was all important, then there are better alternatives around than Bitcoin, but none of the Shit-coins are carrying the value (measured in USD) that Bitcoin is carrying. If the USD becomes worthless as in it dies a death and the world is left to look for a new means of exchange, it won't be looking towards Bitcoin as Bitcoin is just a means of wealth transfer. In times of crisis you might be tempted to swap goods of value for tins of beans, silver rounds, shotgun rounds, gasoline etc, but would you be prepared to accept a few lines of algorithmic code on a USB stick? Same principle applies on an international macro scale and I am referring to a USD extinction event here, not the isolated hyperinflation of the Outer Bulgaristani Shekkel which is exactly the sort of situation that could result in lots of wealth flowing into Bitcoin, thanks to Bitcoins easy interchangeability with the USD.
I think in a global fiat crisis you would be inclined to accept those lines of algorithmic code. You see; trade is an old game. International traders have always been threatened by piracy, border controls, seizure, etc... Bitcoin will be particularly useful in the post-economic collapse where the level of corruption is intensified.
I might not trade internationally, but if I know that Bitcoin is used for international trade; I'll be very inclined to accept it. Nobody will feel safe entrusting wealth to a bank in the near term and Bitcoin offers many of the benefits of a bank account.
The case of "why Bitcoin?" Bitcoin has the largest network, the most current investment, and the widest current adoption. I think it's safe to assume the current adopters are familiar with Bitcoins ability to escape capital controls, theft, counterfeit, and the list goes on.
I can see Bitcoin being very useful in the global trade arena post-fiat.