I think in JA, realism is sacrificed quite often in order to improve gameplay. Let's take, for example, the ratio of available AP per turn and the costs of actions: it allows the player to perform quite a lot of actions before the enemy can act (and vice versa). In reality, such actions take place at the same time. If TBC were meant to be realistic, the number of actions per turn had to be way lower. But I think the game wouldn't feel as good as it does if this were the case, and apparently the devs felt the same way.

If I remember correctly, the range of guns in JA2 was significantly decreased in order to make close combat a viable option on the open battle field - which is quite unrealistic, but it clearly was fun, at least to me.

Consequently, I think Ian's remark aims on people who demand realism for sake of realism only, without being aware of the impact on gameplay, depriving the game of options that'd be otherwise viable.

And now my 2 ct. to the SMGs:

I think the question is if the player has pistols and SMGs and no rifles of any kind, is he better off with the SMGs or not, and I'd say yes, he is. So however SMGs might relate to assault rifles is a bit arbitrary to me if the player has no rifles at hand.