Riot; BEFORE you remove the Will ofthe Ancients, Consider this . . .

Have you guys forgotten why it became problematic in the first place? I'm talking it's original incarnation when it had mana regeneration and a signature spell vamp aura! Granted it's aura only applied to attacks dealing magic damage, so mages would rarely pick it up if they didn't have any other mage on the team; but it was one of the first rush items because it offered so much, like how the morellonomicon has been for the past couple seasons. It had both its mana regeneration & spell vamp aura removed (it kept the spell-vamp for the holder); not only due to having too many bonuses, but since it was making the mages near unkillable unless you had crowd control to interrupt their casting (like how adcs have disgustingly become with autos).

However this double nerf left the item unwanted, as it only had mediocre ability power and near minimal cooldown reduction left. Turning it into a niche item as only a handful of champions could survive sacrificing much more ability power & needed cooldown reduction, which is why the nomicon took it's place soon afterwords. Yet again as physical champions have been repeatedly buffed to raise to power, it's no surprise mages in general have been a rare sight recently; and with less mages means less useful opportunities to bother with this niche item.

I've commented plenty on how most assassins can unintentionally counter mages so I won't explain that here. Except I'll comment on Xypherous stating, "I'm killing Spell Vamp mostly because I'm actually kind of sick of what item availability on this stat has done to these champions. Every single one of these champions have become more binary based on whether or not they can acquire the gold to get Revolver - and every single one of these champion's laning phases has gotten worse and more miserable because of it as we further accept the world in which they rush Revolver." Oh so what about critical chance on near EVERY ranged physical carry; or about armor penetration for assassins then?

There was also the claim that it doesn't work for everyone, again how can it not? Lifesteal already works on the vast majority of AD champions regardless if they're a carry, due to a simple limitation; reduced regeneration from AOE & DOT damage (~33%). This should be simple & effective enough to blanket mages needs while being controllable. Simple thought experiment, vladimir's tides of blood increase all of his healing by 8% per stack with a max of 4 stacks; what if we just lowered his max stack by 1, or made it 7% per stack? It's already an AOE attack so it should be subject to the spell-vamp limiter, and with such a slight nerf, it won't feel crippling, but give some weakness that'll be filled by the spell-vamp item without being excessive either direction. As other people pointed out, champions with built in sustain tend to abuse these items more, so why not just lower their numbers a little to compensate for spell-vamp being a core item for them?

As hardcore fans of dominion can tell you; refusing to support niche status things leaves a bitter taste behind, especially when there's an avoidance to work it out.