The gravestones are there to contrast the skeleton decorations. They tell people be good and you'll get a proper burial. Be bad and your corpse gets put in goofy poses on the porch with a wig or hat or some shit that passersby will laugh at.
If I wanted to make it spooky, I’d have to tear up my yard to make it look like something came out of the graves, and I’m not doing that, which is why I’m sticking with tufts of light up eyeballs.
It's scary to the inattentive. Banging your shin is painful and may cause you to let out an oath, summoning the devil or just embarrassing you in front of the elderly.