Hi,
You say this like it's a fact, but it just isn't.
Slayer arrows only allow massive damage to be generated in combination with FoTW. At upper heroic levels and when running in epic destinies other than Fury, it is not a particularly powerful ability.
Please, show us the Shiradi Champion, Primal Avatar, Shadowdancer, Divine Crusader, Unyielding Sentinel, GMoF and even LD builds which make slayer arrow as powerful as you claim. Making changes to how slayer arrow works will affects other builds apart from Fury archers too.
What makes this discussion so frustrating is the extent to which the developer team is ignoring any points raised which conflict with their narrow and problematic vision of how bow combat should work. It is, like some other posters have observed, like having half a conversation.
Your current approach to dealing with manyshot is going to do more to break certain ranger builds than fix them. It will do very little to address the core problems of archery, equalise 10k and non 10k stars builds, and equalise archery with other ranged styles. Interesting choices my backside.
Thanks.