One change to Mythic Uniques that MUST happen before S14 starts

When I look at the changes to mythic uniques coming in S14, I see one glaring issue which can be solved extremely easily.

Right now, the plan is for the cube to allow you to upgrade a unique to mythic quality. What I had initially thought that does is that it takes the exact unique you have, with the rolls, GAs, etc, and then makes it a mythic unique, thereby maxing out the affixes, keeping the GAs as they are, and basically serving as the capstone upgrade to get your BIS piece of gear (and then you are free to brick it via transmuting).

But no, what it does is take the unique you have and then roll it into a random mythic unique. I'm not 100% if it's fully random or a random one of that item type, but either way that is the worst possible implementation of that system.

You spend time and resources to craft the perfect unique and then you have to play the lottery to hopefully get the mythic unique you want. This is unplayable. This needs to change.