It used to be that if you were flying to Toronto, you pretty much had to fly to ... Toronto. Unless you had your own plane, of course.
Then WestJet started up. This Calgary-based airline, modelled after SouthWest Airlines in the USA, used the same strategy and began flying to underutilized regional airports. Now in addition to flying to Toronto, WestJet flies to Hamilton, London, Ottawa, and Kitchener-Waterloo, to name just a few of its Ontario destinations.
I find it so much nicer to land at the one-building kind of airport, and I enjoy walking across the tarmac, rather reminds me of Casablanca.