Houken is genuinely an interesting character. Just people tend to be fanboying too hard to appreciate, so you're all treating him like a villain of the week. He is a major antagonist, a principle barrier that isn't overcome or trivialized in one-two fights like in shounen. He has always been beyond Shin's league. Capable of fighting at the level that Shin's been aiming towards since before he knew what it meant. His single-minded dedication to his craft should be praiseworthy, not ridiculed as boring.
He is a man who can walk where he pleases, do as he wishes, free and unrestrained. There is no one who can bar his path, and he's been looking for the ones who can. So he can either die by the blade or use their corpses to grow even more experienced, even stronger. All on his quest to become a god of battle. Reach heaven through violence or die trying.
Where's your sense of romance? THIS is the perfect scene for Houken's story to end and for Shin's to catapult forward as he overcomes the barrier that took Ouki away. Stop complaining about it and let us see the magnitude of the life that Shin is about to claim. Houken is no random, faceless mook who should be gutted and ignored.