>Wake up, get on 40kg...holy shit, I'm going to need 2 diet cokes for this

Alright, having thought through the commissar changes, I'm going to try to approaching this objectively. I admit that's hard, since I have been playing this army for 17 years, but here we go. I welcome any critical critiques of my logic if I make mistakes.

Let's say I have a unit of conscripts with no commissar. They have a base Ld of 4. Opponent shoots at them and inflicts 4 casualties. I roll morale, and I assume I roll a 4 (slightly worse than average). The conscripts fail by 4, take 4 more casualties for a total of 8. Drawing this logic out:

>4 casualties = +4 more casualties

>5 casualties = +5 more casualties

>8 casualties = +8 casualties

>12 casualties = +12 casualties

etc.

So without a commissar, conscripts lose double their number from morale. Now, with a commissar who confers Ld 8 on the unit:

>4 casualties = +0 casualties (pass)

>5 casualties = +1 casualty +1 from BLAM = +2 casualties

>8 casualties = +4 casualties +1 from BLAM = +5 casualties

>12 casualties = +8 casualties +1 from BLAM = +9 casualties

Commissars aren't worthless, they force the opponent to inflict a minimum of 5 casualties on average before morale losses start, and they reduce all morale losses by an average of 3 or so. Given the commissar is 30 points and conscripts are 3, he is saving about 9 points of dead people per inflicted test. Not great, but not awful. I think I'm ok with this.

The real problem, I think, is that astropaths are 21 points and can make a unit fearless, plus take away cover from the enemy to boot. Primaris psykers are even more versatile at 40 points, and then there are Inquisitors. Given these other things of similar price that perform better in every way, you are kind of hurting yourself choosing the commissar over them. Why take him, other than you like the way the model looks? I guess his aura means you confer his Ld buff to multiple squads, so that's a point in his favor at least.