I can agree that those 2 weapons need a buff, Kotenok more so. You can find many people requesting those kinds of things respectfully and without cap spamming.
As for the RPK and PKM, both of these weapons have been requested exstensively. All without spamming caps. It is actually easier to do that than not. The feedback also usually goes farther and is considerd more. Also, I could just as easily pick any Soviet weapon not included in the pack and ask for them like it was an obvious choice that the devs missed. I believe there are many to choose from.