I think Kleptomancy Ezreal is overrated
I played a game of Ezreal support and I took Glacial Augment. It turned out that the enemy support was Kleptomancy Ezreal. Here's the postgame.
https://puu.sh/yiy9q/64ed6a72f0.png
A few interesting things. I earned more gold than him even though we had the same CS and kills, and I only had two more assists. My team got more objectives so that's why I had more gold. Kleptomancy couldn't break even with the extra objectives we got. I think you'd be hard pressed to find a better comparison of two keystones on the same champion. Our individual performances in the game were so close.
Yes of course the consumables are really good. I use it on Sona mostly for the sustain. I don't think it's necessary for Ezreal though. I would rather use a keystone that brings some utility to the table instead of generating consumables since, in my experience, Kleptomancy usually gives healing and mana restore and the wards, oracles, etc... are a bit rare.