(a) Real flight simulators are expensive (cost is an order of magnitude less than a real airliner, but still in the millions, and they require skilled operators to put the pilots through their paces),
(b) As I understand it, commercial pilots get paid on the basis of a rather paltry salary, topped up to a much higher rate per flying hour. So there's a strong wage incentive for them to jump in the cockpit of a real plane as fast as possible and get their experience that way rather than spending lots of time training in the simulators.
(c) Modern airliners spend a lot, or even most, of their time on autopilot. Which is not "the plane flies itself" -- it's more like a very complicated cruise control system in a car: you still need to observe and monitor what's going on around you and periodically change some settings governing the vehicle's behaviour. (Just as cruise control won't save you from a bend in the road or an idiot on the other side of the highway crossing the central divider, autopilots need constant supervision.)
But this is not "hand flying". Hand flying mostly comes down to take-off, landing, and brown-pants moments, which is a small fraction of the time a long-haul jet spends in operation. And most commercial airlines are going to take a dim view of pilots who spill the drinks in business class by playing at being a stick-and-rudder hero.
