Actually, I just thought of something- it's more like the "Deal or No Deal" gambit. It's like taking the Banker's offer when there's a 50% chance of getting greater value.
I hate bid whackers, but I can understand it because
a) Money's money, as my dad says. Sometimes you need the money now. Sometimes you ain't got the guts to hold on. I understand this thinking, cause I'm the type of guy who still picks up pennies off the ground.
b) It gives me a chance to take a crack at a few cheapies (Bought some at $1.25- the bid was $1.15 when I entered the order FWIW)
c) Ultimately, if the company is worth anything- a few (or 10's of thousands) shares sold at the bid won't hurt down the road.