Whats wrong with the ak47, the fact that its cheap and easy to produce?
My hating of the AK-47 is just because, personally, I don't like it. Never have. I just think it looks ugly, very un-sleek, and makes me think of Communists (Russians, Viet Cong, Chinese). It's a personal thing in that regard.
Why I'm not to keen on it in gameplay terms is that, mark my words, when it appears, the Bullpup won't be used anymore. It'll become a joke weapon. Because in all respects, it's an UPGRADE and REPLACEMENT of the Bullpup, not a parallel weapon. If it was like the Shotgun vs Hunting Shotgun where both have their niche, I'd be fine. But it's not...not even close...
Why have the sleek little high-capacity SMG-type gun when you can have an actual gun with accuracy and stopping power at the cost of refire rate (You shouldn't be spamming full-auto anyway, IMO!) and ammo capacity (Which is almost balanced by the stopping power; why do you need more ammo if one bullet does what 5 bullpup shots do!?).
It'd be like if someone added in a 'Napalm Thrower' that did twice the damage of the Flamethrower but had only 3/4 of the ammo: It'd make the Flamethrower obselete simply because it does more damage!
It's not just the AK-47 that I'm concerned about with this. If the M-14 Rifle is being added (Which is a weapon I personally LOVE!), it'll make the Lever Action Rifle an absolutely obselete weapon, and I don't like that... Sure, people will find a few pros to using the old Lever Rifle, but everyone will know, deep down, that the M-14 is a far better gun because of the hugely improved damage, regardless of other factors.
IMO, if they're adding the AK-47 and M-14, they need to do something to make the Bullpup and Lever Action Rifle worthwhile to use or they'll basically shove them into the 'there but useless' corner of the Trader's shop with the LAW. Sorry for the wall of text, but I felt the need to make a point here. My personal preference on the weapon doesn't matter as much to me as what they'll do to the games' weapon balance does!