When I play an AD carry, I usually buy a Zeke's. It gives me good early sustain with the lifesteal and attack speed, and the aura can be helpful later in the game. It is a cheap item I can access MUCH sooner than a Bloodthirster (and doesn't rely on kills), and even gives me bonus health and CDR.

So why do I catch hell for it every time I buy one?

If you need lifesteal, get vamp scepter. Get zeal for attack speed.

CDR and health are relatively useless early as an ADC.

That's a pretty fair point, but kind of frustrating. If the build for any given AD carry is identical to every other AD carry, then what's the point of there being an item-buying system to begin with? So one might accidentally screw it up?

Sometimes higher-tier play for this game really bums me out.

Because it provides no raw damage/AD, which an AD carry should really been utilising.

It's better on supports who must be around their teammates the most and supporting them with their skills and often build towards auras for the team. That way the rest of the team can build slightly more offensively with the support helping do an overall team defense.

There are reasonable choices to be made for an AD build. It's just that Zeke's isn't one of them.

Zeke's is a supporty item. While it offers useful benefits to an AD carry, the other options available vastly outshadow it.

Why do all AD carries build the same? Because the build is proven to be the most effective. Boring? Yes. But also the generally accepted best way to do it.

The support should have it by level 13 (if you aren't doing terrible in lane) anyways. It doesn't provide any AD and it the health on it is mainly there to add up with the support. If you buy it and deny your support the chance/option to buy it you are doing a huge disservice to any good support player. Supports rely on the health from support items to be tanky so that's 300 health you're taking from them :/

problem is the same with all ADC's, Building steroid stats like attack speed and lifesteal when you dont have any significant damage is just plain terrible. bloodthirster is popular cause its cheaper than IE and gives you alot of damage for the lifesteal attached to be worth the gold.

Zeke is good for a brawler (top/jungle) or if the supporter wants to boost the ADC.
On an ADC it is not bad, but there are better items out there to push the real suppose of an ADC to his's maximum.

Yeah, that bores me too, but that's how it is. For maximum impact there can only be one way. I liked to play the real-old-Graves as AD caster. It was a different way to play and relative effective, but after all of his changes he is an ordinary ADC like the others. The real old Corki was awesome, too (nobody liked him, because hardly anyone could master him) - Now Corki is an ordinary ADC - crit-champ - too.
Meeeh...

There is only a very little diversity for item builds for each role in LoL. That's the only point I don't like about this game (besides trolling teamates).
But as said, that's how it is...