Original Member and FlyerTalk Evangelist
Join Date: May 1998
Location: Kansas City, MO, USA
Programs: DL PM/MM, AA ExPlat, Hyatt Glob, HH Dia, National ECE, Hertz PC
Posts: 16,619
Because it would be abused by people buying super cheap fares just for the miles. You could buy miles cheaper than a ticket.
Imagine if Southwest did that (which is a bit of an extreme case), you could just go to their website and buy the four cheapest R/T tickets for under $200 and have an unrestricted award ticket. It would totally break Southwest's program and they'd have to scale it back dramatically ... the same goes for other airlines to a lesser extent.