You may be wondering why I'm using the past tense here. It's for good reason -- cogwheels are, essentially, a dead item. Introduced at the beginning of Cataclysm, they could be used in engineering crafted goggles, but that was it. Once players started raiding, those goggles were quickly replaced ... and we never saw anything with a cogwheel in it again. For something that had me really excited about being an engineer, the cogwheel was a letdown of sorts. But that's not the only thing that's been a little off, professionally speaking, with Cataclysm.
Even more interesting, however, is the point of how effective these potions really are in comparison to the other things you can get out there. Obviously, if I'm in a raiding situation, I'm going to choose a Potion of the Tol'vir over a healing potion any day. The DPS boost is far more worth it. If I need a bit of quick healing, I've always got a healthstone handy. Or I can just hit Recuperate, or I can Feint, or I can Cloak, or I can hit Evasion, or I can even Vanish if things get really bad. So a healing potion is literally the last thing I will use in any given fight.
Mobs don't drop potions, so the only way to obtain these Mystical Healing Potions is to have an alchemist craft them. This, I understand to a degree. If you want a cut gem, most of the time, you want to find a jewelcrafter, and if you want an enchant, you'd better find an enchanter, and if you want tailored gear, you find a tailor ... the list goes on. Therefore, it only makes sense that if you want a potion made, you should go to an alchemist. It gives alchemists something to do and makes them feel useful.
I don't use health potions any more.
I don't even use the rogue ones very often. I pick other things to use, or I use the abilities of my class to avoid taking enough damage to warrant a potion in the first place. I haven't learned to go to an alchemist for health pots -- rather than bother with that, I simply don't use them at all. Ever. I found other ways to compensate.
... Now isn't that a little counterproductive to making them less available? Or is Blizzard simply phasing out health potions entirely in favor of DPS-boosting or mana-boosting potions instead? Or, as an entirely different alternative out of left field, was this Blizzard's subtle way of getting us to use those class abilities that kept us alive instead of using potions as a crutch? Was Blizzard quietly teaching us how to play our classes better all along? It's food for thought.