These supposed to be horror stories, vague descriptions are there to make us feel that the characters themselves were too shocked to look at the details, also most of these creatures dwell in the dark where colours do not really matter. To be honest, turning these monsters into RPG bestiary entries kills the mood a little for me.
The figures are nicely painted though
I am with you. For years I refused to read modules or gamemaster CoC games because i most assuredly did not want to know their stats. When I first started a player in a fantasy RPG…I advised them to avoid reading up on their characters potential powers and to absolutely avoid reading about opponents, magic items, and monsters. Mystery once lost is impossible to re-establish, and nothing is scarier than the details of the mind’s eye. I think the film Alien only showed the monster for less than 3 -4 minutes total.
One of my tools as a GM is never refer a monster by its name in the bestiary during the narration. Colloquial names where everything is referred as troll or goblin even if it’s an ogre or an orc.