I see this as a drawback rather than an advantage. As a melee weapon holder, you almost always want to maintain a close distance with your enemy. Unless the developer meant to use knockback as a nerf mechanism, this is pure disadvantageous feature for impact weapon.
Update: if knockback cause damage to both the hostile robot and whatever it bumps into, then I can see the value of knockback.
Quote from: Jiyva on July 08, 2018, 02:11:39 PM
Update: if knockback cause damage to both the hostile robot and whatever it bumps into, then I can see the value of knockback.
It can. At least in Beta 6 though it requires that they hit a machine, whereas in Beta 7 they can both hit and displace other robots as well, damaging them, too.
That said, if you look at impact damage mechanics (see its context help), even then you generally won't want to use impact melee weapons unless you have no choice. It applies damage differently than other weapons, and puts you at a disadvantage. If you want to use melee, slashing and piercing are far better.
But, impact damage is incredibly dangerous to you when wielded by enemies, because your processors will no longer be protected by armor! Brawlers are scary, do not engage at short range if possible ;)
(Remember that, design-wise, not every item or mechanic exists purely to benefit the player, even though the Cogmind can theoretically use pretty much anything.)