I have to disagree about the Topiary Guardians and Crawling Hands; I'm pretty sure they were created specifically so that people could recreate the scenes from The Shining or Evil Dead in their game. I mean, a flesh golem or a mummy isn't very original, either, but originality isn't the point. The point is allowing a DM to use something they saw in a horror book or movie.
So yeah, while most of those monsters are tragically stupid (though most of them have been mocked far more effectively over the years, such as by OOTS, 8-Bit Theater, and any of the comics in Dragon over the years), for a few, it's fairly obvious that the author doesn't understand why Monster Manuals exist in the first place: so that DMs who are tight on time can find stats on something they want to use from myth/fiction/whatever.
On the other hand, man, that horse with wings is so stupid! And besides, the Greeks did the "pegasus" thing, like, 2500 years ago! Unoriginal!