Imagine fighting a challenging encounter, such as Titan Extreme. You have the right equipment, you know the fight, and you've been practicing. You and your party reach the end with ease. Then, at 5% health, the boss wipes out the entire party. There's no defense against it. He does this 20% of the time you reach that stage, and the only way past it is to fight him again and hope he doesn't do it the next time.

That is what three star crafting is like, and it is not fun.

If you go into the craft fully prepared and make no mistakes, you can still make a worthless item just because of bad luck. That shouldn't happen. No matter how difficult, there should be at least one way to guarantee a 100% HQ success.

I'd suggest reducing maximum quality to 4000. That still requires HQ materials, but allows the best crafters to HQ 100% of the time (with difficulty). It doesn't take away any existing crafters' accomplishments, it just prevents randomness from screwing over high end crafters.