What was the point of...

I mean, I like the idea of a character (Bramblestar) who has been misjudged for something in his life being so obsessed with the idea of being misjudged that he just reflexively sides with someone (Hawkfrost) whose situation seems similar to his own, and internalizes everyone else's justified criticisms of Hawkfrost as being just bigoted. I feel that's a realistic plot line and something I've seen with a lot of people in real life. I've often seen people who are judged, whether out of bigotry/who they were born as or their political or religious views, siding too closely with someone else who is criticized for seemingly the same reason, and being completely oblivious to the criticisms of that person being legitimate, and of that person being genuinely horrible, since it's just too internalized/related to the unfair criticism you yourself received. And using that arc for Bramblestar would have been an interesting way to show that despite how much he's convinced himself that he's escaped from what his father was, his life still really revolves around his father because he's still always thinking of how people judge him for his parentage, and everything he does (even the name he got) is all an attempt to reclaim his father's legacy and not to be his own cat. In his very attempt to escape from his father, Bramblestar makes his life revolve around him.
But the Erins completely ruined that by having Bramblestar actually follow Tigerstar and seriously consider killing Firestar just for power. Instead of a realistic character arc that would "regress" him in a completely realistic way that showed he hadn't put his insecurities behind him as much as we thought, we got him being turned completely out of character just for a shallow drama of supposed "moral ambiguity". Instead of getting a story of the long-term psychological effects of being judged like he was, we got a story of him just flipping a switch and nearly becoming evil just for DRAMA!

That being said, the Bramblestar/Hawkfrost arc could have worked without Hawkfrost being Tigerstar's, since Hawkfrost could have still been judged as savage and evil for being the child of rogues, and it still would have played out the same way, that Bramblestar so related Hawkfrost's situation to his own that he just puts some cats' legitimate distrust of Hawkfrost in the same bucket as others' judgment of him for his parents, and dismisses them both off hand. 

i agree. especially since mothwing is still alive and doesnt act like a close kin to bramblestar. tbh she never had super relevant presence after the new prophecy

wouldnt be surprised if they forgot....the only thing relevant about her is her lack of belief in starclan (that somehow still exists after the dark forest battle, but yeah)