Hedging fuel
The purpose of hedging is to give a company certainty over its costs. Thus, you know what your costs are going to be, and can plan which aircraft to fly or not, with a better idea of what routes will or won't be profitable.
Only the oil majors (e.g. Shell, BP, Exxon) by virtue of both digging it out the ground and selling it both retail and wholesale have good information about oil. An airline like Easyjet is not meant to be trying to actively make money out of trading oil - and shareholders get very upset if they think you are doing so.
The decision as to whether to hedge should be taken by someone at least as senior as the CFO - ideally including reference to the CEO. If not (and it's a sign of very poor corporate governance), the bloke who is making a judgment call ends up making big bets on the price of oil. If he gets it wrong and he expects to get fired for a wrong guess, it's very tempting to play double-or-quits. Then he doubles up again. Pretty soon, you end up with Nick Leeson betting al the firm's money and the company going bust.
If an investor wants to buy shares in a short-haul European airline, Easyjet is a good candidate. If they want someone to buy and sell oil for them, there are plenty of hedge funds who'll happily do it for you !