Quote from MTE:
Higher premium does mean greater volatility, but premium also depends on expiration and stock price. An IV chart gives you a better picture of what happened to option premiums in the past. For example, you may find an option with huge premium and when you look at IV you find that the option is trading at 200% IV, and when you look at an IV chart to see where this 200% is in relation to past levels you find that the average over the past 1-2 years has been 40%. You also notice that the same strike call, but in the next expiration month is trading at 45% volatility.
So what does that tell you? It tells you that the market expects a significant move in the stock price prior to the first call's expiration (it is common to see such pattern in biotech stocks where there's an FDA hearing coming). In other words, the higher premium is there for a reason. That is, higher probability of significant move. The risk/reward is proportional.
Looking at IV from various angles gives you a better picture of what the market expects in terms of future volatility without the need to use an option pricing model. That is, all the other variables are either the same or fixed, the only unknown is the volatility.