The problem with this standpoint is that bad mutations outnumber good mutations by such a staggering ratio. If the Darwinian paradigm were true, the earth would be littered with not just transitional forms, but a cornucopia of sad mutations which didn’t live long. The fact that it is not speaks volumes.
I’ve read elsewhere that this is one of the things that Darwin expected to see and said would be the downfall of his system if they don’t exist.