And for the MMGs... I never use them so i can't really say if the change is a big nerf or not.
first shot recoil sucks but 150% increase on nothing is not bad. The problem is that MMGs are the only guns that require you to a.) go prone or deploy a bipod, limitng their usefulness and exposing you to easy return fire and b.) constantly broadcast your position as you fire.
The 'effective' round limit for an MMG is about 50 before you start taking return fire, unless you've cleverly hidden on an angle where someone has to enter your field of fire somewhat blind in order to kill you. Even in this instance, most good players can return accurate enough fire to kill you without much trouble. Literally any gun would be strong and work in this scenario because it's how ideally hiding in cover/defilade works. The MMG just has the off chance of getting more than a couple guys via an ammo belt.
Nobody feels bad when I melt their face off with the ag m/42, the assault rifle with 400 RPM and insane accuracy. But god help me if I manage to find a spot where I can prone without being domed by a sniper or actually get the bipod deploy and kill a guy. Then I'm just a filthy MMG camper that is ruining the meta. I don't even like the guns but they are the easiest way to do one of the assignments for the support class. There is no reason to touch them otherwise, at least on PC.
They are stronger at medium and long range than SMGs and that's it. MMGs trade a laundry list of usefulness in exchange for ammo capacity, but that capacity is largely irrelevant because the instances where you'll be able to put it to use are very limited. The role they are optimized for just doesn't exist in a game where there are lots of players with medium and long range rifles that return pinpoint accuracy. Maybe if suppression under MMG fire was actually a thing, they'd stand a chance.
If they plan to nerf them beyond increased recoil then they should just remove them. There is zero reason to use an MMG over, say, the Lewis gun right now.