Currencies and corps are integral to the
Galactic Milieu, with the main place where "the rubber hits the road" being the corp known in the game as "General Holding Corp" and outside the game as "General Hosting Corp".
GHC is basically the fulcrum of the game's funding, functioning by charging civilisations hosting fees based on the eventual long term needs while currrently not having nearly as much in actual costs due to not yet actually hosting the full level of detail the long term plans call for. (Such as full 3D immersive representations using things like OpenSimulator.)
This may initially sound as if the civilisations are paying way more than cost for the hardware infrastructure upon which the game runs, but really it just motivates the civilisations to own shares of GHC, so that they actually like the fact that GHC makes a profit by charging fees in excess of its costs.
The currencies are also integral to the game, because the conversion rates shown at
http://galaxies.mygamesonline.org/latestrates.inc are used by GHC to allow the civilisations to pay the fees in any of the listed assets.
The same conversion rates table is also used by the Deuterium depots that both General Mining Corp and General Retirement Funds maintain in the inner layer of defense galaxies surrounding the galaxies in which the civilised worlds reside, so the intergalactic mining corps can sell Deuterium, and sometimes also Metal and Crystal, against any of these assets, subject of course to availability of the asset (a depot cannot pay in an asset its mother Corp does not own, and mining corps who are still paying off their startup loans are of course credited in the currency their loan is denominated in, against their loan.)
So yeah, these currencies and assets are totally integral to the game, ultimately they are how the game development and hosting and bandwidth and so on are financed.
Also, conversion to and from fiat currencies tends to be handled within the clan / guild / etc (groups) systems within the game, so that for example Brits (members of Britclan) wanting to convert United Kingdom Britcoins to or from the British fiat of
the planet known as Earth would do so through the clan officers of Britclan, Canucks wanting to convert Canadian Digital Notes to or from the CAD fiat of the planet known as Earth would do so through the clan officers of the Canuck clan and so on.
(A good motivation possibly to join a clan or guild or somesuch or to form one yourself?)
-MarkM-