I don't usually spec grenade abilities, if ever (unless it's a stimpack and not actual grenades). I'm sure so do many others. Ever tried replenishing grenades on Gold?.. Good luck with that, esp. if there's more than 1 grenade user on the team. I see speccing grenades as a waste of skill points.
Whaaaaaaaaaaaaaaaattttttttttttttttttttttttttttt!!?!!!??!!??

Well, I guess at least you know the next step to git gud: respec all your grenade characters and put NO LESS than 21 FULL POINTS in any grenade power.
No exceptions whatsoever. Go. NOW!
And use those damn thermal clip packs! What do you have them for!? You wanna put them in a museum!?
No, seriously. I can't think of a single bigger "doing it wrong" thing in this game, other than not shooting your gun maybe. You might want to correct it asap.