Because they say people are "freight" and they have to move the "freight" and you have to pay for them to move the freight and the more freight there is the more you pay.
We don't call passenger "self loading cargo" for nothing at work.
Of course they have to charge more. These industries are finding ways to make a profit with all the oil prices going up and other costly expenses.
In this climate, if they don't make a profit, your flight ticket would be a whole lot more $$$$$$$$ possibly to the point that the average person would no longer be able to fly. It is a large amount of this profit that makes a usable buffer to keep the prices down so you can afford to fly. The profit is used to off set the real cost that the oil price rise has really produced. Flying from a A to B is not the only thing that is effected. Maintenance costs have increased at an equal rate. As a paying passenger, you only see a fuel surcharge or having to pay for you coffee or bag of peanuts, you don't see the bigger picture. Companies like the low cost are losing money hand over fist. They are using the profit buffer in an attempt to ride out the oil costs. They will either raise ticket prices too or go under, it is just a question of time for the answer. Rolls Royce driving profit making and share holders become secondary priority, staying afloat is what it is all about until a new business model is put into practice or the cost of oil becomes more realistic ( :-/) With the old oil price, cheap tickets and a profit was possible. Today, it is so marginal due to the oil, well, we only have to look at the actions of the big carriers. They want to keep the prices down, it attracts passengers. One way to make extra money is to say you have to pay for your extra bag or food. They are not forcing you to take your entire wardrobe on holiday with you or ramming that $5 sandwich down your throat. Most of the extra charges can still be avoided if you think about how you want to travel. After all, a two or three hour flight, do you really need to eat, or do we use the food to break up the flight and give us something to do. And if you ar$e is so wide it takes up two seats, why should you not pay for that extra space. You have taken a second seat of a paying passenger, why should it be free.
Matt
"A bit of a pickle" - British translation: A catastrophically bad situation with potentially fatal consequences.
PETA

People Eating Tasty Animals.
B1 (Cat C) licenced engineer, Boeing 737NG 600/700/800/900 Airbus A318/19/20/21 and Dash8 Q-400
1. Captain, if the problem is not entered into the technical logbook.........then the aircraft does not have a problem.
2. And, if you have time to write the fault on a napkin and attach to it to the yoke.........you have time to write it in the tech log....see point 1.