Oh, because if sages get WP buffs to melee damage then it would follow that shadows would too.
No, absolutely not. It's all about removing a restriction that only Sages/Sorcerers have, causing the main stat to not increase all of their attacks but only Force attacks (they are the only ones who don't have a main stat that increase two categories of damage).
Melee bonus on Willpower ? Shadows and Assassins already have it, Consular and Inquisitors who don't have chosen an AC yet have it. Only Sage and Sorcerers don't have it.