The reason for currencies is really simple. We need them to continue having carrots to get you to play. If everything cost sP, people who've been playing for years could purchase them immediately on release, and go back to whatever else they were doing.

Instead, we release features that have currencies (Quest points, for example) that require you to complete a task (quests, participate in a plot, post on the forums) that is an activity that we want to promote, and that is the only way that you'll get those items. OR users who are doing those tasks will buy them and be able to sell them at an advantage to themselves to the people with sP/CSC.

If currencies on that page are confusing maybe better communication on that page as to where they come from would be handy, but as it stands new currencies (and existing ones) are an excellent gaming mechanic for us.