A stable price is good for bitcoin but in my predictions only a higher prices would attract more investors. Stale prices would make merchants hold their bitcoins as well as miners. Stable prices are opening point of higher prices. My prediction is higher prices than we can see stable prices.
Stable prices would promote adoption though. From a merchant's perspective you don't want to accept Bitcoin and then discover you've actually made a loss if you didn't trade it back to fiat fast enough. Stable prices would convince merchants that as a measure of value Bitcoin is stable - and therefore they would be happy to hold them/spend them (as is Bitcoin is designed for - for use as a currency - rather than a commodity).
We won't have stable prices until we don't grow considerably. Just forget about this. We are too small and our price changes violently with only few big buys or sells.
Also, there are a lot of childish thinking in Bitcoin at the moment and investors that don't know what they are doing but are reacting very emotionally to every price action. They are just pouring gasoline on the fire and making volatility even worse.