Little assburn. Tangent normalmap for body (Patreon)

I'v made tangent (classic blue ad in armor) normal for body instead of current object space.

What i done:

1. Make copy of CBBE body as regular armor.

2. Remove model space normals support.

3. Make quick and dirty baking tangent normal from muscle model to CBBE from 0 in SP

Results you can see on screenshots.

Can anyone explain to me for what reason we are dealing with this object space shit for 10 years ? May be there is some critical reason?