They shouldn't be in the game.
Ever since DH1e, they've never made sense to me as characteristics. I get why they're there (as a holdover from tabletop), but that's not a good reason at all. Other than WS and BS, every other characteristic acts as an actual natural characteristic of a character. Whereas WS and BS would make a hell of a lot more sense as skills, given they're, you know, called Weapon Skill and Ballistic Skill.
I know this will never get implemented given the goal here seems to be backwards compatibility, but wouldn't it make a lot of sense to change WS and BS into skills (or remove them entirely), and make Per and Ag the characteristics that govern competence with guns and melee weapons, respectively?
The only major issue I see this creating is that Agility suddenly becomes even more overpowered than it is now. But that could be fixed easily enough by relocating some of its applications to other characteristics.
Edited by Tom Cruise