There's a possibility that these skins are models for the path of the titans thing in Cataclysm, like whichever path you pick are the tattoos you get.

It seems most liekly these skins are for NPC's.
I'd consider the "Sunwalkers" a little bit. Bleeding wings speaks of an "Icarus" type reference to me, possibly they're an anti "Sunwalker" movement.

I'd doubt it's character customisation sadly and even more doubtful it's to do with the Path of the Titans.

It was pointed out through tipline to WoW.com during Blizzcon 2009, that among the official images that were used for Cataclysm announcement, there is one were an Orc character stands with distinct imagery on his upper torso skin that looks like a tatoo, possibly hinting on some new character customising tech being implemented.
WoW.com never acted on the tip.

www.worldofwarcraft.com/cataclysm/_images/screenshots/ss13_hires.jpg

I love how much the lore is evolving when cataclysm comes along, it kills this tranquil feeling i've had about azeroth for so many years, "what theres an evil demon in the dark corners of another dimension, sure we're all fine here lets go kill it" or "theres an army of Undead forces which have been ignored for 8 years but they're all of a sudden threatening destroy! lets keep our homelands peaceful" and now "oh know! our land is destroyed by a dragon who eats gods and entities for breakfast and the peaceful faction leaders have been over thrown and now we're in total war" its like if you step back and look at wow everything is getting gradually worse little by little then shit hits the fan and we're all screwed, i love it :3

that was a reply to taurens becoming more warmongering btw, i didnt really make that clear >_>''