"The full implications must be understood and carefully weighed before choosing a different course." (emphasis mine)
i.e. you are required to have a good reason not to do it.
i.e. you are required to have a good reason not to do it.
Words mean things, especially in standard texts. You can't just carelessly rewrite sentences using not-quite-synonyms like you're doing here.
Oh, and that "must" is not a "MUST". Had the text said "The full implications MUST be understood ..." it would have been a proper requirement by the standard, but this lower-case "must" is just normal part of prose and not the magical "MUST" word which formally imposes a requirement.