I'd like to require an "unambiguous" statement that you not only have the right to remain silent but can prevent further questioning by invoking it if we're going to do it this way, but it's fair. If they tell you you don't have to talk and you do it anyway, that's hardly their fault. Similarly, the Fifth Amendment protects against compulsions to testify against oneself, but doesn't preclude confessions or other voluntary admissions. Otherwise a suspect advised of his rights could literally get away with murder by confessing and THEN invoking his right to remain silent. Obviously in low scrutiny locales where suspects either aren't advised of their rights or even have them routinely ignored it would be a problem, but that's not really a problem stemming from this decision, rather, a deeper one.