It's simply a wrong statement. There are not only speculators on the market, but also merchants and (since Bitcoinica launch) also hedgers. Sometimes people are selling because they want to cash out or buy coins, not only for speculation. When I want to cash out btc->usd *right now* and I accept current market price, it's *not* a loss for me, but it can be a win for a speculator, who sold coins on higher price days before. This is clean win-win situation, which isn't possible without a speculation.

Actually speculation make exchanges much more usable for merchants, because they can sell or buy Bitcoins at any time, no matter if there's another merchant who want the oposite transaction NOW; this makes price much more stable, although many people won't agree with me.