<<<Does BiA still have allow you to carry two primary weapons? Because while I could understand the need to balance gameplay with realism, I feel disappointed in this decision.>>>
Let me explain the decision...
The game is about fire and move tactics. A typical player, we find, tends to like to either be the squad leader (he hangs back and orders his men to do the hard work) OR there's the player that wants to use his guys to suppress the enemy while going in for the kill himself.
But, most players tend to enjoy alternating roles - mixing it up. Sometimes hanging back and suppressing while commanding the guys to assault, other times doing the assault.
So, if you only could carry one weapon what tends to happen is that a player who wants to switch roles in the middle of a mission will have to back track and scour the battle field looking for a different weapon to pick up. That's really boring and lame.
By giving you two weapons, you can make decisions about your load out. You can have an assault weapon and a suppression weapon, and switch between them rapidly when you want to switch roles. OR, you can have a suppression weapon and a sniping weapon - I tend to like to play the game like a supression->snipe game when I play on the PC. OR, you can carry, say, a BAR and a Thompson. Use the BAR on the move to suppress while you're closing, then switch to the Thompson for the close assault.
There are a whole bunch of combinations that just enhance the tactical options that the game provides.
Besides, we know, historically, that there were many soldiers who carried more than one weapon. We've got a picture of one paratrooper who's carrying TWO MG-42's AND THREE MP-40s!! Found that one in the National Archives - I've included it in the extra features (which, BTW, are very cool - over 70 Bonus features and you don't have to pay extra for some special version to get them).