There's some infantile obsession with this phrase in every layoff thread. "I take full responsibility" is partly a polite way to say that they aren't blaming anyone else for what's happening, it partly means "I'm the one making this decision" and it's partly ceremony for the sake of appearances - if you're outraged that the CEO of a multi-billion dollar company is using this language, that's a problem with you, not with them.
It's like being indignant when a friend or a colleague replies with "I'm fine, thanks" when they aren't fine, or when they say "I can't complain" when they're in fact capable of complaining - it's perfectly normal language for the situation and it's understandable to anyone who has developed the skill of not taking every word literally.