The public usually doesn't care about this, they may get interested when they realize it's one of those damn B1900s, but otherwise one big airplane with jet engines is the same as the next. What matters is if an airline can turn a profit, and the type of airplane is not the deciding factor, although sometimes it does have a pretty big effect. See how Allegient has managed to make a profit. Aquisition cost is probably one of the biggest issues in this industry, and the routes and revenue is just not high enough to justify the aquisition cost in most cases. Operating cost is another huge one, but the capital cost of a new airliner is crazy, and you have to fly it for something around 20yrs before it "breaks even". Given this, when you get your ducks in a row to secure funding for a "fleet", you damn better well be able to turn a nice profit, but hey, what is the purpose of airlines? I'd say it's to lose money and provide steady jobs for management