User blog comment:Vectus13/% Health shred option for AD casters?/@comment-9048637-20131206060002

AD Casters are in an extremely good place right now; League of Bruisers is slowly strangling the life out of the traditional tank, and assassins are always high on the top of everyone's "OMG RIOT PLS NERF" list. (That doesn't necessarily make them nerfworthy, of course, but it is a pretty good hint that they're not underpowered.) They don't really need something to make them even stronger.

And heck, even if that weren't the case, health is meant to counter AD casters, because they can itemize a lot more freely for penetration than their sustained damage counterparts, since penetration is basically their go-to offensive stat anyway due to their high base damages, whereas sustained damagers need to worry about things like AS and crits. So giving them a percent health shred route would take way one of their main balancing disadvantages.