All of those examples are monsters that you, I, and any other experienced DM have probably run dozens if not hundreds of times; and thus we've largely memorized what makes them tick.
If I've ever run a Yellow Musk Zombie, though, I don't remember it; and I'd have to check all three books to find its write-up and stats. Or a Fog Giant - there's Giants in all three books but after the basic Hill-Fire-Frost-Storm, which one's in which book? Or an Yrthak, which isn't in any of the 1e books but is in the original 3e MM.
If there's to be a new monster book, it's an opportunity to tighten up and consolidate the stats for all of them - as in, every monster D&D has ever had - in one place; specifically intended to make it easier for a DM to find and run any given creature during play. Leave the fluff and lore and fancy art for other books.
Do it!