What Bill Miller said make sens. Bubble can show people how strong bitcoin really is, and possible outcome in the future. People need to understand that, as long as bitcoin is used as an investment, there will be bubbles. When people start using bitcoin as currency (as its meant to), bitcoin bubbles will stop.
Aside from that bubble also make bitcoin popularity grow. When someone saw a stock price growing, it will definitely the talk of the town, encouraging listeners to invest on that stock. Same goes with bitcoin, no matter how strong the warning of the authority of the bubble bursting, people will continue to invest in it. In return, more supporter, higher price and the market will be test when the bubble pop up.