There are over 600 known inherited genetic diseases. There is only one known positive mutation, and it's not clear yet whether or not it has negative side effects.
Therefore it seems easy to conclude that enough negative effects from random mutation make it pass stage two, that the genetic gene pool will see continuous degradation. And that not enough positive mutations occur to offset the negative load.
It's de-evolution. Man isn't coming from the apes, he's going to them.
We are fully evolved. Most creatures that we see are fully evolved. Who knows where the next evolutionary step will come from, but I would keep a close eye on the slime ponds.
Positive mutations tend to get ignored. If someone is 10% smarter or stronger than the general population due to a mutation, how would we notice that the mutation existed? Furthermore, positive mutations eventually become the norm in a population, so they eventually become the status quo.
However, a negative mutation is easily identifiable because of the unfortunate effects of such a mutation.