Cons are sub par because they can't focus DPS. They get their vet 2 bonus accuracy and a vet 3 cooldown iirc which is nice, but that's it. It's still 6 dudes with rifles when yellow cover and durability buffs are flying around. They get a MASSIVE durability buff at vet 3, but that's easily offset by enemy weapon upgrades. And the biggest problem with all of their power coming from their vet is that if you happen to lose the squad that is it. It's gone. No attempt to recoup that loss. Lose a gren squad? Hurts. Slap an lmg on them and they will again burst down models. Not as frequently but the power is still there. Cons have no such redemption. For a squad that's supposed to be kinda trashy but expendable they are the least replaceable squad in the game.
This is why I suggest SMALL passive improvements as the Soviet player techs up to sort of offset the lack of weapon upgrades and allow cons to be replaced if need be. In the end they would still be conscripts, but maybe slightly less trashy...
Its also much, much easier to lose a vet 3 grenadier squad than a vet 3 conscript squad.
If you've lost a VET 3 conscript squad, you have to not be paying attention for a very good amount of time. Its not like they're getting 1-shot or even 2-shot by literally anything in the game.
Soviets are by far the best faction in the game, conscripts are very good, 4 cons can easily hold territory and keep team weapons functioning long after they should and they function very well into the late game, supporting those team weapons, snaring tanks and supporting either guards, penals, or shock troops.
If you decide not to build them, then you also have penals available instead, which utterly destroy any counterpart, except ambushing sturms, although with vet, you can melt sturms too. They remain amazing at anti-infantry role through-out the game, if you leave them without the PTRS upgrade.
Conscripts are literally my favorite infantry in the entire game, especially for their staying power and ease of vet and utility, the only thing that I would see go from them is their flares, to be replaced with something more useful.
I like conscripts being just that, conscripts. It feels good to win by drowning your enemy in blood, just like the USSR did historically, it tickles the RP'er in me.