As some have pointed out here, at one time the airlines used wide bodies , DC-10 etc on domestic and holiday routes. They have all switched to narrow bodies. Load, frequency and turn around mean better economics and money rules.
What is interesting is Atlantic traffic is going the same way, see Norwegian and Primeria.
I haven't flown the A380 but everyone I know who has loves it. But then people loved the Concorde, even with the cramped seating.
The good thing is, smaller planes = more jobs for pilots !