Tattoos are fine if it's decorative, and for a non-ugly girl, naturally it can't be too large or outrageous. Say up to 3x6 cm it can add some edge or altitude and unique personality.
But too often tattoos is used as a statement on its own: "I'm fringe, I'm outrageous." "I love physical pain, I'm weird". Once you went down that path, physical beauty become second (or fifth) priority, which is bad for porn.
(going further OT) one genre of JAV that's missing and I'm constantly wondering about is yakuza porn or yakuza-fantasy porn. If you don't know what I mean: check out Crying Freeman. A woman, invariably beautiful, almost supernaturally beautiful, would have her whole body covered in tattoo as a sign of devotion to a yakuza boss, since tattoo is a proof of devotion and manhood and bravery, the woman also become magcially feminine by doing this very manly thing. Of course I don't suggest any AV actress get any real tattoo, but why not use temporary tattoo to make a yakuza fantasy porn? Won't you like to see Rion full body tattoo, only for one vid (better perhaps, just one scene)?