The world has certainly had its fair share of IOU scams, yes! In fact my original conception of Splash was to be "Ripple with nothing but the pure currency" (the XRP). (And, of course, without the pre-mine.) This would then act as a testing lab to see just how well the consensus algorithm works, especially under DDoS attacks, Sybil attacks, etc.

However, in the end I decided to leave the full IOU-managing functionality in place. I had two motives: (1) it's there for those who want it, and it can simply be ignored by anyone who doesn't want it - they can choose to only ever use the pure currency (the XSP); and, uh, (2) you'd be amazed how long editing other people's code takes... it's easier to leave it in than to take it out!

If, after Splash is up and running, someone wants to fork it to "mini-Splash", with nothing but XSP, created purely by proof of work, and ledgers managing the XSP, created purely by the Ripple consensus algorithm... then yes, that would be an interesting experiment too.

(If they took it just one step further, and changed the consensus algorithm to a find-chain-with-most-work algorithm... then they'd have pretty much reinvented Bitcoin. )