Thing is, i dont think the game as it is is broken. Not in that respect.
In games like counter strike nobody used the Shotguns, or the pistols, or anything other than AK / M4 and maybe a sniper rifle.
Guess what, thats exactly what happens in the real world. People dont bring a pistol, or a UMP to a battlefield. They are used in close quarter room clearances only.
So yes making all the other guns like the pistols, smgs, machine guns etc.. of no use would be more accurate, but then it would just be like CS where nobody used the different guns.
How useless was the M249 in CS ? nobody used it because it wasnt as good as the Ak / m4 in 1 on 1 short range warfare. Which is what its like in the real world.
I would much rather be able to kill people with smgs, and shotguns, and pistols as it means that people vary what gun they use. Its more fun to be able to choose from lots of different weapos knowing they will be of use Unlike in CS where everybody just used the assault rifles and nothing else.