Down in England title caps like that went out around the 1950s. Compare say the UK Guardian with the New York Times and there is a huge readability difference. US print newspaper design is very retro, like the UK was in the nineteenth and early 20th century.
It's true that some of our newspapers here (I'm in England) have moved into the new millenium with their headings, but alas quite a few textbooks and business reports still languish in the typographical dark ages, even new ones.
As far as I can tell, title case is still one of those quaint ideas that you teach in English classes at school because the syllabus says so, even though it is an objectively inferior approach and is not particularly popular in real world usage any more. (See also: Almost any comma usage when handwriting letters or envelopes that you were taught as a child; not splitting an infinitive, beginning a sentence with a conjunction, or ending a sentence with a preposition; spelling out certain small integer numbers in full; and your teacher's pet view of the Oxford comma.)
