While particular builds having an affinity for different support skills is all well and good to create variety between playthroughs, one that seems a bit unwarranted is Psions being the only build that can cost-effectively invest in persuasion/intimidation. For one it locks any build without Will into either ignoring speech skills and killing their way through every encounter, or sinking a huge amount of points into it to make up for the malus from low Will. Additionally, it doesn't really make sense that Will is the pure determinant for both of these stats, most persuasion involves reasoning, so it could easily derive from Intelligence instead, and a big part of Intimidation is looking the part, so character with high Strength should also be able to intimidate someone.
Basically the suggestion is to make Persuasion use the higher of Will or Intelligence and Intimidation use the higher Will or Strength, similarly to Melee Weapons using Strength or Dexterity. In a similar vein Mercantile could scale from Will or Intelligence, which would open it up to being used by non-crafting psi builds.
