Under the logic that speculation from traders hurts a currency, FOREX must have ground the dollar and yen to dust by now. Speculators might cause some volatility but not having them also causes a massive amount of inconvenience and logistical problems.

Bitcoin would not be nearly as useful right now if it were not able to be exchanged to and from national fiat currencies. These speculative markets providing liquidity are really what makes bitcoin worth having until it reaches a critical mass where it's accepted nearly universally (probably not in our grandchildrens' lifetime). I'd argue that these speculators are probably the biggest boon to bitcoin's development since the original algorithms.

Think about it without your idealism and you'll realize that if you could only trade bitcoins directly for goods and services that could then only trade them to other people directly, there would be far fewer people taking bitcoins right now. The ability to cash them out and buy a plane ticket or a cup of coffee from your convenient merchants is key to early acceptance.

I like this way of putting it.