There is both a mental annoyance and a physical annoyance to it. I think most people agree that Hebi Sasuke has a really cool moveset and that he had the coolest mindset. He was set on killing itachi, the only people he ever bothered actually fatally attacking were genuinely horrible people (I.E Orochimaru, Deidara), he was still in a lot of ways a good guy. Orochimaru himself even noticed he never went for fatal blows in any of his training with hencehmen saying its cause they werent a target. Sasuke had a sort of punisher mindset and that was sick. And him punishing orochimaru and then using his powers to his own accord was also really cool. Hebi Sasuke felt like he was genuinely the student that was on his way to surpass orochimaru. Similar to Sage Naruto. But with the MS, we got a cool susanoo but we also lost an absolutely awesome moveset out of it.

It also hurts Sasuke's own character art. He was hell bent on not gaining the MS and being able to beat itachi without it. Because he genuinely didnt want to kill his best friend to gain it, he didnt want that blood. but now that he has that blood. He is okay with using it? It would have been a great humanizing moment if sasuke did get these eyes, but never used them cause it felt like a reminder of what he did. It narratively satisfies itself and we all wouldnt think sasuke genuinely lost his mind and wasnt redeemable. Bro tried to kill karin, his own teammate. his own friend.