@Xel and @Vortok, I don't think that's an accurate assessment about Steady Hand.

One thing dropping the success rate will do is knock down the "guaranteed 100% HQ" macros out there a bit, because it's no longer guaranteed and you wouldn't have the CP to afford the next Touch up to make it guaranteed. They'd still be good ways to get HQ, but they couldn't be 100% mindless with the way they are now. The fact that these macros exist is a BIG reason why it's "too easy" to HQ.

The second thing it would do is make reliance on Hasty Touch (or, for some people, Rapid Synthesis) more dangerous. These are gambling abilities. You get them for free because of their unreliability. If you make them the entire focal point of a tactic, then you should be getting unreliable results. This is not the case currently. That 70% -> 80% difference is a huge part of this.

If you want to eliminate RNG as a negative factor, use the more expensive abilities and HQ components. If you're willing to add in RNG as a factor, use the cheaper abilities.

The bottom line is, if they reduced the success rate of the Steady Hand abilities, people HAVE to use HQ components to guarantee things. It doesn't degenerate into a heavily RNG based system unless you choose to use the more heavily RNG-based abilities and refuse to use anything other than normal quality items.