Blackblood as it was implemented in SB was actually a pretty great addition to the job, due to how much it interacted with MP through Delirium, TBN and Quietus(including that early patch change here obv) and how its acquisition wasn't as static as it is now, which made it feel different from other jobs' resources. Giving DRK a second resource that's actually linked with the existing one added more reactivity and evolved the resource management - both very important aspects of the job's(original) identity. It's only in SHB that it's basically become a reskinned Beast Gauge - SB Blood worked quite differently and synergized really well with the entire kit.

The issue was that rather than adding it on top of existing HW mechanics, SE's cut out or changed too much of the original kit, making the end result feel more like a loss than a gain in depth to many vet DRKs. It's a damn shame, because HW DRK with added Blackblood could've been truly fantastic, but I guess devs were afraid it'd be too much for the players to handle.

Honestly the main mistake in SB was that instead of evolving the existing job they tried to outright replace some of its mechanics(procs, og Darkside). SE clearly hasn't learned that lesson though, as in SHB instead of trying to rectify that and returning some of the DRK's HW roots, they must've concluded that if there's complaints then the entire job was bad to begin with and changed it even more drastically than in SB, basically doubling down on their mistake. I guess everybody saying that "people miss the HW version" wasn't clear enough feedback somehow.