Originally Posted by gosflyer
I've always wondered about this. With the generally big difference in price, wouldn't you be better off buying a regular fare and paying the $100 or so, plus even the fare difference, to change it? Just asking

Couple of reasons. Clients don't like seeing additional fees and charges. And in case of last second cancelled trip, we would have to waste a whole tix, not just the $100 change fee. So it's better in long term to buy full fare.
Plus, some trips are last minutes and only full fare class remained.
Another 'stupid' policy : We can only buy economy tix for domestic flights. But sometimes, last minute full fare econ is more expensive than discounted F. But nothing we can do. Must buy econ, and hopefully get upgraded to F.