I think its very hard to buy a pic for xxx Dollars, playing a game, lose it and you know the pig is now only half worth. PLUS the chance that you can loose it to your opponent or it will die.
Summary: too much negative effects can happend. But on the other side, hey its a game and this are the roles...no risk no fun!

Question: When to opponent get that pig, is this then also downgraded? Then I think it's not ok, because this is a smaler reward then!