......why???

Wasn't she described as being physically abused?

Ar the epilogue Holmes is asked about Stapleton being an obvious culprit regardless of the dog due to him living under a false name nearby, and Holmes pretty much answers "Yeah well oopsie, who knows?".

For Sir Charles, okay. Sure. Heart attack. For Henry, what would be the excuse? "Mauled by a phantom dog, oh well, case closed"?

If Henry is just shot and placed with a gun on his hand, there's no forensics back then to prove it wasn't a suicide.

He forces his wife, who he constantly beats, to pretend to be his sister even before he hears the Hugo Baskerville story from Dr Mortimer and thinks "A cursed ghost dog, yeah that's the way to fucking murder my uncle and cousin so I get their money". Makes no sense whatsoever.

But it's risky as hell, he had witnesses of his wife, the caretaker of the dog while he was playing detective and stealing footwear wearing a fake beard in London for no fucking reason, and the odds of it failing were huge. Am I the only one who got possessed by Scott Evil's soul and thought "Just fucking shoot him!"?