Because its statically proven ost is currently the worse faction.
Rifles and re buff allows it to trade well against early okw, but now ost is going to fall behind further.
Usf rifles are a beast late game with vet and upgrades.
Cavs and asseng are doctrine and we pretty much accept they are going to rape grens and weapon teams
Calling the RE change a buff shows exactly where you're coming from, at least. Their dps stays exactly the same and the only major change is they'll now do less damage to vehicles.
USF Rifles are pretty good at vet 3, yeah, once they've got the RA bonus, 20% cooldown reduction and 30% accuracy bonus, sure. 120 munitions of BARs and three levels of vet are enough to make even Ostruppen deadly, however, so that's a non-argument.
You admit this change is helpful for tackling OKW but are concerned Ostheer sucks shit still, fine. Go tell them to buff Grens reinforcement cost or something. But as it stands 280mp RM are standing only more or less equivalent to 250mp Volkgrens and immediately fall behind once vet 1 and/or STG44s hit. And again, at short range you should be losing to RM anyway, be it Volks or Grens, and if you're playing Ostheer you've got the best HMG in the game right there at T0 to try to zone out riflemen. If you screw up and they flank the MG or your mortars or whatever, you're also, again, going to lose to the rifle squad anyway.
Why not instead be happy the only non-doc USF counters to static ostheer play besides the shittastic mortar are getting nerfed into obscurity? Your concern regards team weapons after all.