I believe you are right, for some reason I though it was 3 POP but I can't remember if I am confusing 221/223 with the others.
The 76MM is only 120, fuel same or similar to most other MEDs in the game. No one needs it for those units so why would they need it for the 76MM.
The KV-8 is 145 Fuel I believe, again not much more than a regular tank despite it having heavy armor. The expended MP is better served building a cache for the team so the entire team can get tanks out a bit faster.
The KV-2 is the same price Fuel wise as the other Heavies and locked behind CP. In most high level 1v1s once most of your army is built fuel usually isn't the limiting factor, MP is. In all game modes, if you go with a double AT gun stall fuel is not a concern in the slightest.
1 truck is not really a problem, its that most players who use them abuse them and make 3 or 4. I posted a game recently where both teams had players that abused the hell out of it and by late game both players were MP starved. At work, so I can't rewatch it to check if they take POP or not.
EDIT: To clarify my stance, I think for Soviets in particular with Cons the unit itself works great as MP usually isn't a problem even though fuel is really in short supply. In team games, I think it is a bit greedy as it doesn't help the whole team.
For OST/OKW, the MP can be a bit wasteful depending on how the game is going. Any wipes to Vetted Grens will cause massive MP bleed until they can get their Vet back(same with Obers). Therefore it will delay the expensive tank anyways as you are now MP starved instead of fuel starved.
your army will be limited at the start, but trucks increase BOTH fuel and munitions (with lend lease you can easily find yourself with hundreds of muni and little ways of spending it). They are manpower efficient for the player specifically and they can be used on points with caches
it is greedy, but the player in question will have a lot of fuel income, allowing for him to easily rebuild tanks that he loses, the limiting factor usually being manpower.
I think that the way you play with both industry and lend lease (in team mode) is to shit out tanks (if you have a fuel point, i think you can reach around 45 fuel per minute pretty easily, allowing for you to make a t-34 tank every 2 minutes).
also IMO the 76mm is pretty trash, I do not think it seems really worth it, KV-8 is good but you only need 1 + loses relevance once more AT is deployed.
I'd say that the only downside of the truck is that neither doctrine has any muni sink ability, so you float muni a lot, unless you love mines