It wasn't a cost cutting effort. It was an attempt to gain space on newsstands.
In 1940, a comic was ten cents, as was Time, Life and almost every other circular.
By 1972, most magazines were several times more expensive than a comic and produced more income and profit per unit. With limited space, do you display a book that sells for a dollar or one that's 20 cents. DC tried to make their books more valuable to sellers.
Marvel announced a line of 100 page books, to go with their short lived 48page for .35 cent books, but instead went with the Giant Size (68 page) books. It was twenty years before Marvel printed hundred page books.