There's a really terrible trend of requiring magic spells to be cast to "invoke" 4th and 5th amendment rights. You have a right to remain silent, as the Supreme Court has codified it; it doesn't make any sense to talk about "invoking" it specifically. You don't have to declare "I invoke my First Amendment rights" as a magic spell to avoid being prosecuted for writing something on the internet.
But I don't disagree with you; I don't think we should have to voice our rights. We should be able to hold the government to the task of protecting those rights, rather than having to protect ourselves explicitly.