I feel like Blood Frenzy would be more useful and strategic if, instead of being a constant health drain, it simply took health when using any ability. Each time you use an attack, the effect gains a stack increasing both your damage output and the damage inflicted to you. It would function relatively the same, but would be more manageable because you have full control over damaging yourself in order to deal additional damage.
It reminds me a bit of Blood Magic from Secret World Legends, where the whole skill line was about balancing self-damage in order to deal more damage. Every time you cast a Blood ability, you gained "corruption" on a sliding scale. At escalating intervals, your abilities would harm you more, deal more damage and reduce healing effectiveness. At 100% you dealt max damage both to your enemies and to yourself but could not be healed by any means, even yourself. Instead you had what were essentially "corruption" dump abilities. You cast one of these damage or healing abilities to consume some corruption and reset your meter.
We already know they aren't planning to make any changes, but I feel like having more control over Blood Frenzy would be more interesting than just a toggle that makes combat feel sloppy.