Whilst agreeing that PTF is wrong, it appears that with market conditions such as they are, it is here to stay.
Why is a PTF pilot with 250hrs more likely to have an incident than a SSTR or bonded 250hr pilot? They have a large financial interest in getting it right and of course hope to be kept on as a result of their performance. Unfortunately just the smallest glimpse of the imagined nirvana is enough to open some cheque books in the mistaken impression they'll remain employed. As said before, in this market it's not going to happen.
Experience levels are the same and unless the PTF pilot has failed miserably during any previous employment attempts then each can fall at the same hurdles during training and subsequently. Many experienced pilots have bent aeroplanes for any number of reasons.
I don't think the discussion is really about maligning the abilities of the PTF candidate rather it is the morality of these schemes and the effect it has on the livelihoods of others. Unfortunately it brings in cash and that makes the bean counters very happy.