I just wanted to address this too: mining costs are a factor underlying price, but ultimately price dynamics are determined by buying & selling, which are in turn determined by humans & emotions. Mining can be unprofitable for weeks/months without nethash suffering (DRK demonstrated this). Or mining profitability can be huge for long periods of time, sustained by strong buy pressure. Or the price can crash and burn, causing miners to leave to the point where nobody bothers anymore. Equilibriums might work on paper, but in practice it's never that neat.
Bottom line is: you can't trust that the price will equilibrate to butt mining costs after a period of hype & speculative adoption. It really could go in any direction depending on competition, media attention, tech problems, all kinds of things really. And the market can be fickle. So it's better to cover your bases where you can.
DRK had pretty good marketing and media attention. Monero hasnt even started yet...
MRO doesn't even have a wallet... we need that first.