Only because that would be too honest. But it actually has to be accidental. There's only two possibilities, accidental or planned. Since it's supposed to happen due to random mutations, it surely can't be considered planned.
I am always curious about it when people make this dichotomy. Accidental, in my mind, means there was an intention one way and things actually happened a different way. Planned means that the actuality matched the intention.
But the vast majority of the universe doesn't have an intention at all. Instead, it works via natural laws, which are neither random nor planned. For example, the orbit of the Earth is due to the gravity of the sun. The sun has no intention, but it produces the gravity that keeps the Earth in exactly the orbit it has.
Evolution has *two* parts: mutation and natural selection. Mutation isn't related to the needs of the organism or population, so in that sense it is random. But it is due to things like radiation or chemicals in the environment, so is subject to the laws of nature.
Natural selection is also distinctly not random. Which organisms survive to reproduce has a highly non-random component to it.
So, your claim that there are only two possibilities: accidental or planned seems to not just be false, but to be trivially false. it assumes that there is an intention in everything, which is something that is pretty clearly wrong, as far as I can see.