Agreeing with RBG here. Many apparently novelty sets can work very well because the opponent is misguided into thinking it has the best option. Just two examples.
Infernape can run a quite powerful pure special-attack set, which theoretically would be walled by Blissey completely. But who in his right minds would switch a Blissey into Infernape? Most Infernapes carry Close Combat, so she wont dare. That Infernape is not using Close Combat actually, but its very presence in the movepool aids him even if he does not choose it.
Also Mixgross (Meteor Mash/Earthquake/Grass Knot/Hidden Power Fire) can work thanks to a similar trick. Most people fear the CB or Agility set, and so switch into Skarmory, since even CB Thunderpunch may fail to 2HKO. But most of the times they will rarely expect over 60% damage from a surprise HP Fire. An even more amusing present for Hyppowdon, Swampert (Grass Knot) and Scizor (again HP Fire). Of course, you eschew great moves like the elemental punches, Explosion, Agility. But even if apparently inferior the surprise value do really compensate for this.
So, even if Unaware is the best option, Shockproof could be a neat surprise since everyone will expect the former.
EDIT: I dont think it would seem fanboyish, at least I think it is less fanboyish than giving an ability only for the sake of the artwork - as many people suggested to do now and before. With this idea in mind, even Battle Armor Pyroak could be seen as a fanboyish "OMFG I hate hax so much I dont want my wall fucked by CHs". Of course, this is not my opinion about Pyroak, and since I try to be consistent, I think I should not be against Shockproof too. It is just a directly beneficial ability for a pokemon. Not that strange, really.
We created it? Who cares? We already created pokemon, moves, abilities. Nothing new.
It is an ad-personam ability? Again, who cares? Mountaineer wasnt? Persistent Wasnt? Technician wasnt? And, about existing pokemon, Serene Grace Skymin, anyone? really, a lot of pokemon, CAPs and not, have ad-personam abilities, be them unique or not.