Vacation sellback is a jobs issue. There is no doubt about that. And it does incentivize more productivity.

But its more than that. Ultimately, you can argue it's a fatigue issue. Which ultimately is a safety issue. The whole point of vacation is to relax, rejuvenate, recharge, rest, etc... Humans need that. And we need more of that as you get older.

Granted, everybody is different. Some need more rest than others. But getting rid of vacation sellback was also an effort to protect all of us from those goofballs who fly sick and tired no matter what for the almighty $$.