Wineman, were you checking advance purchase fares? That's not the purpose of Hotwire (I'm surprised you could save $20 if that was advance purchase). Airlines don't want to sell advance purchase seats at a further discount. Airlines do want to sell seats which will probably not be sold to last minute flyers (i.e., the middle seats not in the front of coach) -- that's where the savings are.

Hotwire is not for most leisure travelers; it's for price sensitive business travelers (or going to a funeral or visit a sick relative).