Originally posted on 12/30/2012:
because a freeplay is very different than real money
with a real money bet you get stake+winnings back
freeplay means you only get winnings
so if you use it on a -110 bet, your 110 freeplay returns 100 if it wins, meaning under a 50% return (factoring in the chance you lose). If you bet it on a +400, you are getting significantly better value.
If you used it like regular money, you might bet it on a -400. That means best case scenario, you only get 25% back from your freeplay.