With the key word being could, I would agree with you in this particular case with regards to this particular aspect of this particular law.
My point concerning date rape is directly in relation to you (and I apologize if I made it seem like it was directed as stating you were in favor of rape), but in that with serious offense (i.e. rape, murder, drunk driving) we do not want officer making decisions as to what are good laws and what are not or even whether the circumstances of the events warrant the charging of a crime or not. I used date rape as an example, because there are some people who feel that such cases are blown out of proportion. If such a person was a police officer you would not want them to simply dismiss the case lightly. Similarly with drunk driving, if an officer felt that drunk driving laws or some aspects of them were wrong you would not want them to dismiss it lightly either, since it is a very serious offense.
IMO, this particular case was a miscarriage of justice. There was a violation of the spirit of the law by upholding the letter of the law. And this is exactly my point. The process is supposed to be that the police uphold the letter of the law, and the courts uphold the spirit of it.
You are also correct in saying that reality and the way things should work do not also coincide, and this is deeply regrettable, but the fix to this is not to increase the discretionary powers of the police to a wider array of crimes.