From my perspective- yes, using a normal Assault Rifle at ranges less than 20 feet is a rough thing, as its size gets in the way of fast accurate targeting in a CQB setting. It's one of the reasons why the switch to the M4, which at 10 inches shorter than the M16a2, is more usuable in such conditions.
As having used both in such environments for training/et al, I can see why the penalties for Assault Rifles.
If you look closer at the other rifles listed in the book, you will note that some of them are better than others and in looking at how the various weapons look, I can see the reasoning for said modifiers.
Shogun rifles look little more than glorified SMG's so their penalties to hit at range make sense.
M74 Carbine is supposed to be good at short range... which is repped in the stats. I think it should be better at PB but thats where the HMG trooper comes in... and they can have a few.
So from a game a rules perspective for me, they are fine. Your opinion may and will differ.
