[li]
Where are you getting this? Just because some people roll around with a 99 dharp/ghorn brd doesn't mean that everyone or even most people do. Having capped magic haste isn't certain regardless of accuracy needs. Unkai Haidate +2 are often a worthwhile tradeoff anyway.
Has nothing to do with 99harp/horn, even with a +2 brd you will spend 70%~ of your time with a marcato'd march (ie capped magic haste).
What real scenario do you find yourself in where you need to make large accuracy swaps and you don't have capped/near capped haste? None unless you are bad at this game.
Unkai Haidate +2 is also illogical if you're in any situation when you care about hybrid/DT purposes.
You're gaining ~12 accuracy at the cost of 2% haste and large amounts of defensive, dumb.