It looks unnatural and unfitting for the nether. To reproduce, use the seed -4661555592816429823, then go to the nether and go to -16 88 -80 to see a great example of what I am talking about. This glitch can be found pretty much anywhere near the nether ceiling.
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Confirmed for 1.13.1.
Can confirm in 1.17-pre3.
gaspoweredpick
The cave and ravine generators (even in the overworld) have a max height value specified up to which they can remove blocks. For nether structures this is y=120 (y=248 for the overworld) and the cause of this bug.
This was probably added to prevent the generators from reaching the bedrock layer and possibly removing it, but since they are unable to remove bedrock blocks this isn't actually necessary, or at least it could be set to y=128.
This bug is actually a lot older when it comes to nether caves. I've tracked it back up to release 1.6 (from 2013), but it has probably been a thing since the introduction of nether caves in alpha 1.2.