If you happen to be travelling on a particularly cheap fare it is possible that the cost of transporting your bags could exceed the cost of transporting yourself. For example, I've just booked a return flight to Germany for �1 each way (plus two �5 booking fees, making �12 in total, including all taxes, charges and fees). If I was to take hold luggage (which I won't be doing) it would cost me more than the ticket price.
If I was to check in one bag each way, I'd have to pay a total of �20 for the return flight. If I checked in 2 bags the total fee would be �60. If I checked in 3 bags the total fee would be �100. Those figures assume that the
total weight (irrespective of the number of bags) didn't exceed 15kg. If it did, there would be an extra �15 per kg to pay, in either direction.
Such pricing structures are to be welcomed. They're completely transparent and much fairer than giving all passengers a free baggage allowance.
http://www.ryanair.com/site/EN/faqs.php?sect=C HARGES
Some of the biggest costs in running an airline are associated with paying for the fuel, which has to be ordered based upon the weight on board the aircraft. It's perfectly reasonable that those people who have checked bags should pay more than those that don't. It's also reasonable that the airlines should discourage customers from checking in more than one bag. Budget airlines only have 25 minutes to get one lot of baggage off an aircraft and the new lot on; they need to keep the number of bags to a minimum to avoid loading delays.
Chris