The "promise" is to replace it withStill asking for less material with no promise to replace it with anything. Also, just because you (the general you) don't like something doesn't mean it shouldn't exist.
a) free time not spent sifting through low-quality monsters, and
b) some of your money back because you're buying 1 supplement instead of 2.
Sometimes less really is more. It's not something to act incredulous about, even if reasonable people may disagree about which specific monsters are high enough quality.