Admittedly, I don't have a lot of MMO experience outside of FFXIV. The only other MMO I've played is FFXI, and the crafting in that was PURE RNG, with very little a player could do to affect the odds. You clicked Synthesis, loaded the ingredients, and then hit the "OK" button. No matter how high your level, you had a chance to fail (something around 5%, I think), which could cause you to lose none, some, or all of your ingredients (chosen randomly). If you were above the level of the craft, you had a chance to HQ, with the best odds being if you were 51 levels above the craft, netting you roughly 50/50 odds of HQ. Of course, it's not possible to be 51 levels above the highest crafts, so you were stuck with the basic HQ chance, around 1%. You didn't see a lot of HQ endgame gear, and the pieces that folks managed to produce (purely by chance, no skill involved whatsoever) were some of the most expensive items in the game.
Compared against that, the crafting system in FFXIV is amazingly fun. You have real control over how things turn out. Admittedly, it's a system that favors mathematicians; leveraging probabilities to produce the best results over the long term is what crafting is all about. Some folks, though, just can't seem to wrap their head around the idea that just because a CAN go catastrophically wrong doesn't mean that it WILL. Murphy's Law is a big, fat lie. And, even if that odd failure crops up, you have plenty of successes to balance it out.
What was WoW crafting like? Just drop in the ingredients, and out comes a finished product? No HQ chance or failure risk?
Edit: Also, you mentioned this would never fly in Raid mechanics... except that they DO. Critical hits. Unless there's some limitation on how critical hits work in raids that I'm unaware of, every hit has a chance to crit and do extra damage. A crit or two here and there isn't likely to cause problems - but what if every hit is a crit? Not likely, of course, but it could theoretically happen. Hasty Touch is much the same way; a couple of Hasty Failures and you'll still be fine, but if all or most of them fail, you're screwed. It's the same deal.