One of the issues traveling with some of the low cost carriers is that they do not have interline agreements with other airlines in case the flight is cancelled etc. You have to wait till they have their next flight, and then that flight has to have a seat for you. They cannot "protect", or involuntary reroute you on another carrier. The price may be lower, but if you are willing to pay more to fly on a for example Lufthansa, Air Canada, then if something goes to hell in a hand basket, you will have that protection and you will get rerouted. Another issue is for your baggage. If you bought a low cost carrier from Toronto - Frankfurt, some low cost carriers will not auto transfer your luggage or interline your luggage to another airline since they do not pay for this agreement, that is why they are low cost, and if your connection is busted, well, then you are hooped
As Scylla mentioned, pay more