Grens should be supporting team weapons, which Ost has good options for. This is why they have the best snare.
To get around low squad size for recrewing, you should really be using a HT or bunker.
None of this makes sense. They are supposed to support their support weapons, but get wiped in the blink of an eye due to their low squad sizes. They fight 5 to 6 men squads, of whom most get double lmg upgrades, whilst grens got this taken away at one point. This is again not a very sturdy support role.
They are supposed to support their support weapons, but have a low squad size which means they can't effective support their entire support weapon system when one of the support weapons gets decrewed...
Now don't get me wrong, grenadiers aren't horrible. But their roles are wonky and, if I might say so, quite frankly; counter intuitive.
Edit: as for the suggestion to add a fifth man or an hp buff, I think none of these will solve the issue. The grenadier issue reflects a general issue with CoH2, where other designs are far more superior to the outdated design of vanilla factions. Ostheer has the hardest case of what I call: "General outdatism". Where the Soviet faction could be dealt with by buffing certain units, making the entire roster sort of more effective and the corner stones solid, the Ostheer faction would require an entire redesign. Not going to happen lol.