I trade to try and lend atmosphere to wherever I go. I also try to do the most junker-centric runs out there to provide example so there's more inter-house Junker to Junker trade instead of everyone out there doing Slaves-Cardi.
I have no real use for the money aside from bounties, or maybe paying someone to redesign Puerto Rico.
I can't ever see abstaining from it as it's so central to the RP of my faction.