I still deeply regret abandoning my hydra pet back in Wrath of the Lich King. A bug in one of the daily quests in Sholazar Basin allowed hunters to tame a ghostly hydra, oozeling, or crocodile. Blizzard fixed the bug, but allowed everyone to keep their pets. In my defense, we were only allowed to have four pets in our stable at the time, and there was spirit beasts to be had. Do you know how heavily camped Loque'nahak was back then? You think cross-realm zones are bad?
Before Wrath added a couple of extra stable slots (which cost gold, by the way), hunters only had two stable slots throughout vanilla and BC in addition to our active pet. Then Cataclysm came along and let us tame a whopping 25 pets. I'm pretty sure the server hosting the Petopia forums spontaneously exploded in the back of a room somewhere, ruining some poor IT guy's day. It felt like it could never get any better for a pet collector. Then patch 5.3 came along and Blizzard said: "You guys want, like, 30 more pet slots? Sure, here you go."
The new slots were welcome, but just how does one tame 55 unique pets?. Once you've tamed every rare and hunted down every spirit beast, what else is there? The tallstrider, of course. Get one in every color and have your own fleet of tallstriders. Tallstriders are awesome! Maybe even more awesome than sporebats.