Phillip went into a bit more detail at the MOSES discussion. He specifically called out BITCOIN as problematic, since the supply is limited by design, to prevent inflation. Instead, he pointed at the value of an inflationary model, which results in a more stable Virtual/Dollar ratio like the Linden has enjoyed.
By allowing the assignment clients to generate currency for supporting the domain operations, the rate of currency growth should be close to the rate of demand growth. By adding Currency “sinks” ( like a per/voxel creation charge), we should be able to manage the rate of growth more closely, and maintain the kind of stability he is discussing.
(Reading between the lines…) I’m sure there are a myriad of other design decision factors, like the Feds recent moves into the useful virtual currency markets. It sure seems like those moves make the concept of a centralized currency “transfer” service more likely as a additional revenue stream. High Fidelity handles all the reporting requirements and takes a “transaction fee” for converting the Crypto to “real” currencies and back.