Currency is an important economic good in itself.
Money helps to facilitate efficient division of labor by providing a common medium of exchange to which all other resources can be compared. Large multi-way deals would yield the full benefit, but are difficult to negotiate. Also, in a pure barter economy, an economic agent needs to have available to it an exchange rate for every possible pair of goods it would need to trade. Money lowers the computational overhead of conducting commerce. Easy portability and divisibility are desirable but not vital characteristics.