Part of the frustration for me is that as a single player (or dual player) experience, generally I'm either a) happy with things being overpowered or b) am willing to take personal limitations to control how overpowered things are and limit how powerful they are. With sniper rifles it's easy to limit myself to one, or not put supressors on all of them - so while they could adjust the game for balance, it's not as important as what were the laser blast accuracy of MGs. That said, I also found MGs horribly overpowered, but couldn't exactly limit myself (I already only had one operator) and there's not really something I can do to limit their power.
So I agree that something had to be done on the software, since I couldn't manage a fix on my end. But what was done changed them from too useful to outright near unusable. Part of that issue is the outer extent of their cone. With regular overwatch I can control how far out I want my mercenaries to target things, which limits long-range low-chance-to-hit shots. With the MG that's not the case, as the change fixed the laser-focused accuracy (a good thing) but in turn makes it so when somebody enters overwatch, you're firing at long range (and not hitting) wasting their limited interrupts.
I also do wish there was more "balance", making every weapon in the game an option from some angle (ammunition, durability, range, accuracy, mods, etc.) in order to avoid the JA2 trap of escalating equipment. As for the Gewehr, it's certainly powerful when it makes its appearance, but for the time it truly shines, ammunition is rare enough to limit its breadth of use in the squad. By the time you have sufficient ammunition, you've usually broken through to the main island and have started broadening your weapon base (which to me is fine).