Seriously, I feel like that was the only thing we needed. It lowers the skill floor, ups Scholar's personal DPS, and doesn't encourage counter-intuitive gameplay for optimization. Admittedly it's not as impactful as '10 potency on Broil III' but I think buffing it to 250 potency and simply not doing the Broil III buff would have been enough to get the numbers right without changing much. Their stated issue with ED ("You're casting it too much, heal more") is purely due to their fight design to begin with so I fail to see how it helps. Seeing more and more Energy Drains per fight is a sign that SCH has mastered said fight. There's nothing wrong with that.
Just in case someone at SE is not familiar: The problem with Ruin II is that it deals too little damage relative to Broil III right now. Specifically to the point that it's better to force Energy Drain between your Broil IIIs (ie. clipping) if you don't have to heal. In order to fix this problem, Ruin II must have a relative potency of at least 5/6th's of whatever hardcast spell (Ruin/Broil/Broil II/Broil III) you're using. Shadowbringers changed Ruin Mastery to make Ruin II at 80 potency less than Broil at each Broil rank respectively, which is absolutely awful to play with. In 5.3 with Broil III at 280 potency, the number Ruin II needed to sit at was 240. At 290 come 5.4, Ruin II needs to be at least 250. And the higher that is without going over, the less of a penalty it is overall (but clearly SE wants it to be a tax, so it should be slightly over 5/6 but they can err towards the maximum penalty). Admittedly this means Ruin II is also less useful as a movement tax, but that is generally fine because being a movement -and- weaving tax means you can reliably account for more Ruin IIs being cast in the first place, and therefore see it tune down SCH's maximum DPS threshold accordingly. The other changes would also make sense if this change had been implemented. You're losing a tiny bit less than before (100 ED + 40 Ruin II vs 150 ED) for using a single Aetherflow heal out of place, but it feels better to play overall. Broil III hits harder and still pushes SCH's overall DPS higher across all skill levels because you're getting more casts in at the low to average skill range, and the DoT changes compensate for the potency lost on Energy Drains which brings up the skill floor.
I'm not saying these changes are bad (to some extent they might be necessary regardless, but because of this oversight they fail to hit the mark), but seeing Ruin II sitting untouched this long makes it hard to see the argument for why SE did so many of the other changes in Shadowbringers. To me, it's necessary just to bring those other changes in alignment with their overall goals. Quality of Life can depend purely on numbers being tuned appropriately to facilitate your ideal gameplay. This one's easy to do, and likely would have made the Broil III buff unnecessary in the first place.