It's a psychological thing. Having a price set by mathematics gives people a sense of stability. It's like why people don't wildly speculate on fiat money. Math can give bitcoin the sense of fiat (law), only it's the laws of mathematics. Of course there will be fluctuation just as there is with all fiat currencies, but it will be mitigated. This whole Bitcoin phenomena is an experiment, I just think this may be a helpful tool. I just don't trust centralized exchanges because HSTs and bots can have such profound psychological effects on people that cause them to panic buy and sell.