Won't work.
It's got nothing to do with D&D either.
Back in the 1950's, The Creature from the Back Lagoon prompted the audience to scream in terror and young girls to faint. Now, if I showed it to my six year olds - who are hardly the most worldly 6 year olds in the world when it comes to media consumption - they'd probably giggle.
In the 1930's, when Bela Legosi played Dracula, there was serious discussion of the film being too intense and horrifying. Even with a toned down monster that never reveals his fangs, it still left its audiences in real and palpable terror. Now, it's less intense and monstrous than your average children's cartoon.
The problem isn't with the monsters. It's with the audience. We are now in that period of a civilization which is called 'decadent'. We've all become jaded and blaise from overexposure. You can't scare people with their imagination anymore because they've just been exposed to so much of that and nothing terrible resulted from it. You might as well try to scare a ghoul that grew up in a mausoleum with the horrors of old bones.
Fear is like a valley. People are only afraid of those things that they have no experience with - snakes for most city dwellers, for example; or, of things that they've had such intimate experience with that its resulted in severe trauma (maybe haven't actually been bitten by a snake). We're in the middle, having been exposed to fire continually but never having been burned. So, of course we can't make monsters scary.
Now, if all you are trying to accomplish is make the players fear losing their characters, or to make them choose to run away, then that's fairly easy. But if you want the monsters to actually be scary, well good luck with that. You'll need to wait a few years until people have been burned more.