Giving them utility does not mean that they will be pushed into an ultra niche role. There's plenty of options to give utility instead of pure combat power via their weapons.
Again, like what?
Grens have medkits, pios have incread sight, both can build bunkers, they obviously can't be given sandbags, explosives make no sense on them, neither do sweepers, 7th man adds pure combat power, they already have fausts, there is stock AT squad, it doesn't make much sense for them to repair and already PGs get that ability through another doctrine, flares are completely unsuitable for them and their theme.
These guys were guarding railways from partisans IRL.