I have to balance my game playing with the rest of my life. I pick up KSP and play for a few hours, then due to life / work commitments, might not be back on the PC for a couple of days. So for me my gaming is a purely pleasure experience / escapism and I have no requirement to waste 4 hours of my time smashing into Jool as I try to aerobrake for a mission to Laythe. If I want to waste 4 hours I can go and weed the garden, paint the decking or try to sort out the Megajolt timing and fuelling on my Haynes Roadster.