It seems most moral philosophers say that morality needs intrinsic value
Intrinsic value has traditionally been thought to lie at the heart of ethics. Philosophers use a number of terms to refer to such value. The intrinsic value of something is said to be the value that that thing has “in itself,” or “for its own sake,” or “as such,” or “in its own right.” Extrinsic value is value that is not intrinsic.
Many philosophers take intrinsic value to be crucial to a variety of moral judgments
And this isn't the same thing as non-accidental:
As J. Michael Dunn (1990) notes, some authors have used ‘intrinsic’ and ‘extrinsic’ to mean ‘essential’ and ‘accidental’. Dunn is surely right in saying that this is a misuse of the terms.
Does any philosopher say that all moral value is non-accidental, but not intrinsic?
Philosophers do sometimes seem to characterise "value" as being non-accidental: e.g. Wittgenstein in the Tractatus 6.41
If there is a value which is of value, it must lie outside all happening and being-so. For all happening and being-so is accidental. What makes it non-accidental cannot lie in the world, for otherwise this would again be accidental. It must lie outside the world.
moral values have their transcendental existence outside the domain of contingent facts
Value is non-accidental
Wittgenstein [is]... speaking of value as a non-accidental feature of the world