Regardless of pack howi performance Major and his barrage are very cost efficient.
I have yet to see you tell something is not "very cost efficient" about literally any unit or ability, regardless how bad it was.
Yes, major arty looks amazing on paper, everything looks amazing on paper.
M-42 looks amazing on paper and I'm 100% positive that if someone made a topic on how bad it is, you'd be the first one screaming "how amazingly cost efficient it is for its cost and how it should never be changed".
But its a gimmick that provides muni strain and is of limited use.
Imagine you paying 60 muni every single time you want to use a panzerwerfer barrage and its max range is 50.
Barrage looks amazingly on paper, but would the unit be useful on the long run?
Same thing for major, most squishy unit in the whole game and a constant muni strain if you want to utilize him, making it impossible to save for weapon upgrades or off-maps.