Ok. I am sorry I have to do this, but I fail to see how any of the points you are making are connected.
The frenzy set change is not similar to the brimstone situation at all. Post-nerf the strategy and purpose of brimstone was still the same which is to land the brimstone debuff, they only changed an aspect of applying the debuff but its purpose remained the same. Whereas with this frenzy change they are completely changing the strategy and purpose of the set by making the turn meter gain based on debuffs instead of loss of HP%. A lot of people were focusing high resistance on their frenzy gear which counteracts with the new mechanic which makes their investment worthless.
What do Taras and Marichka being overpowered or the state of live arena have to do with Frenzy Set? For me, I use my best frenzy gear on two of my strongest champs in live arena. The news of this change to frenzy has already made me lose interest in doing live arena, and when this change takes place I will need to rebuild those champs in new gear and probably my other champs too since it was apart of the strategy I use. I fail to see how this change will improve anything in live arena. I only see it having the opposite effect.
This is not a minor issue because it is in no way helping keep any game modes alive. It is a major disruption to players accounts who use frenzy set.
Please share a precedent of a champ that was buff/nerfed and their intended use changed? Then maybe you have a point. If you want to compare changing a champ to this change to frenzy set it would be like taking a champ like Krisk and instead of him being a tanky support champ turning him into a squishy attack based nuker. Everyone would be rightfully irrate.
If you never used frenzy set before you probably don't understand how its purpose was changed to something entirely different and far less effective.