the reason to know the worth of money is ... "roleplay"
things might be wrong - they might be abstract - but a great motivator for "doing things" is money or a reward.
in a classic roleplaying game, you may have gotten 10 gold pieces for a tough but short quest ( like cleaning out a tomb of its undead ) - and you knew knew that it was worth it, cause that was what payed for your brand new warhorse. - you could relate 10 gold pieces to the price of a good horse + equipment.
it would also have felt "wrong" if the same quest had given you 1 million gold pieces. - cause then any SERIOUS roleplay would have wondered - "why the hell would i keep my adventuring days going?"
so knowing how much what is worth - and balancing that out is important.
in sirius - inflation becomes greater - the richer one becomes. - that is natural - when you have much, you don t care for little.
so - if traders are ALL basicly "freelancers" ( meaning, they make their profit themselves ) - and they hit lets say ... 1 million ... how does the character justify to keep going?
if one million is too little - how about 1 billion. - still not retired?
so this is about roleplay. - when is a character "happy" with what he has. - some might say "i am never happy, you can always have more" - but thats not quite how it works. - give the utmost greediest man 10 billion $ - and he ll run out of ideas what to spend it on sooner or later ( hence his greed turns to boredom )
when does money become less of a motivator.
maybe we should really reform prices, perception of money and rewards.