Byakko's Haidate were still some of the most highly sought after melee pants. There were other options for some people, but really. Nothing came out that beat them until AF+3.

With newer gear and merits sky became easier. Also with the way the game was played. When the first generation of players hit 75 haste gear was limited and largely overlooked.

As players came to understand the system better and as different gear became accessible you no longer needed full alliances to farm sky, and it's true finding 18 people who needed sky would have been a challenge in it's own right. But there still were people who needed sky, and there still were people who would do sky... and Byakko never became so easy that he could be killed by two players. He was still largely worth killing.

True the same may not be able to be said about Genbu or Suzaku or Seiryu beyond the seals needed to pop kirin, but Kirin, even though he could be zerged was still worth killing.