the reduction in price of turbo prop aircraft (caravans, conquest's...) means that more charter operators and private owners are adding turbo prop (some light jet) aircraft to the fleet.
Also going from single engine turbine to twin engine turbine is not totally un common and not that difficult, I had a look at a PC12 once and christ it was more complex than the old citation for sure.... probably harder and faster to fly too.
I still have a chuckle at the requirements some companies have for aircraft that I don't meet and have plenty of hours in...
Industries evovle, some people get dragged kicking and screaming... I wish we could say that because of the safety and greater standards in training we are now producing more compenant pilot's... I think the aeroplanes are just getting smarter