Negligence is not generally regarded as a criminal matter since it involves no mens rea . Without such criminal intent, traditional reasons for convicting somebody of a criminal offence become nonsensical. In this light, the legal objections to Morgan fall. It is not the case that rape is differently treated from other offences against the person. In all such crimes, the lowest standard is one of recklessness.
Murder is homicide with 'malice aforethought'.
But it would be bizarre to institute a crime of gross negligence rape. Unlike homicide, sex cannot be entered into accidentally or negligently. Sex is defined by the way it is carried out - on the basis of a conscious decision. The law recognises implicitly that unlike a homicide, where there is a dead body to account for, the sex act in itself is not harmful. Put more strongly, mens rea is the basis of society's condemnation of the guilty.