Originally Posted by
kyuven
Like I said, many bosses already do this, but they go a step forward and have the "randomness" on every pull rather than every instance. They just don't have MANY attack patterns, and most of them are reserved for EX primals and Coil.
And again, they TRIED having full RNG attack patterns, but even their testers had too much difficulty with them, so they yanked them from the "core" and made it into Savage Coil.
What you want is a fight to be completely different each time you zone in...which creates a problem: "Save scumming."
If one pattern is preferred over another, a team will exit and re-enter until they get the one that's easiest to deal with. Especially if they're as drastically different as you're implying you want them to be.
In the end, you'd just see forum posts complaining about how X version is impossible, Y version is too easy, and no one wants to do Z version because it's not Y version. If it's in the DF, people will complain about people bailing when Z pattern shows up and calling them pansies for not wanting "a challenge."