I think every final villain has issues because Oda refuses to develop them. Imagine if the Akatsuki was never developed and every time we see them it was just them talking about how Naruto is ruining their plans. Or imagine in HxH, mereum and Komugi relationship was offscreened, then of course we wouldn't find Mereum as appealing as he was. Akainu, BB and especially Imu all have those issues.