Honestly, the abuse of rights via the commonplace coerced consent is far more egregious than the pre-Miranda coerced confessions.
I see no reason why police shouldn’t be required to inform the detained of their right to refuse the search.
Terrorists aren’t intimidated into consent, and marijuana isn’t worth the police state abuses.
In fact that is law in Oregon. A person must know they are (and in fact be) free to refuse consent and leave when consent is requested. No threatening to get a canine unit, standing in front of your car or door or otherwise blocking you. Anything like that will get a case tossed out of court, even if you give consent.