Grens I think are relatively fine where they are. They are a strong core infantry, but they have their counters and their durability issues, not to mention losing too many models early game is detrimental due to their reinforce cost of 30, same issue as USF, where losing too models early on delays tech and new units. And in smaller games, I generally don't lie spending all those munitions until the late game since first purchase will likely be the med bunker, maybe mine sweepers, and then it depends if you're force to faust/use nades.
I also must be the odd one out on PGs. I think PGs do pretty good damage overall with and have their place as mid-short range combatants and become bringers of death with vet. You just don't charge them like assault troops, unless it's a support weapon or weak infantry units. Nor like Grens, will they usually ever be the main line infantry because of the reinforce cost. I would say usually 2 max when with 3-4 grens and the accompanying support weapons. You probably don't see too much because, on my random assumption, most people prefer to stick their their build and not differentiate since it pushes them out of their comfort zone. It also means I'm the only player who usually tries to build a Brummbar in smaller games because it's there in the T4 building
.