I think your second point actually points to why the first might be wrong. There are huge ranges of jobs that a humanities degree qualifies you for that you can't get without one--- even a bunch of stuff that's unrelated to the degree, like HR or various secretarial jobs. In engineering, if you have no degree, you at least have a chance of convincing someone that you're a great engineer by doing independent work, and even large companies like Microsoft and Google do hire people without degrees. In the humanities, though, it's very hard without a degree to convince someone that you're "just as good" as other applicants who have degrees; you generally won't even get a second look.

So I'd almost say the opposite: that if you aren't going to do engineering, a degree is definitely worth it, but if you are, it might be more questionable, and depends on what exactly you want to do, and what your outside-out-school credentials are.