Let's talk about spell vamp

So today we're going to talk about spell vamp, or rather the lack of spellvamp. Now before you say anything about items, I want you to go look at item sets or go in a custom game and check the 2 item's that most likely come to mind when you think Spellvamp. These items are: Will of the Ancients and Hextech Gunblade , yes these use to give spell vamp, but sometime I'm not sure when they stopped, as of right now only 1 item actually gives spellvamp, this being Hextech Revolver.

Now you're probably writing "But they heal based on damage dealt" That's great and all but that's not spellvamp, and even if that was acceptable, go look at the amount of items that give true lifesteal, there's 7 legendary items alone, and 2 building items. So my question is: Why is there only 1 spellvamp item in the game that's not even a legendary item? Some people might say the healing on damage dealt still does the job, but as someone who used to build both Will of the Ancients and Hextech Gunblade on Evelynn I can confirm: It's not as good nor does it do the job. And let's not forget Morgana whose passive is literally made useless by this, for those of you who don't know her passive give's her spellvamp based on her level up to 20%. Now while she still gets some benefit from this if she builds enough AP it's still drastically nerfed compared to what it used to be when we actually had spellvamp.

TL;DR: There's 1 spellvamp item and 9 lifesteal items and I'm a salty AP champion main.