Since the 1970s (from my personal experience) we don't train soldiers to use the bayonet (or the rifle its on) as a weapon. My DI was asked about this in basic, and explained it this way..."the ARMY, in its infinite wisdom has determined that if you are in hand to hand distance of the enemy, the odds are extrememly high that at least one of you will have ammuntion,...therefore we are not going to waste time and resources teaching your sorry asses how to use the bayonet!"
The story is true. I was there. Fall 1975, Ft Leonard Wood, MO. BCT (Basic Combat Training)
Now, if you were going to be Infantry...you would likely get more, in AIT. In Basic, we got just what I posted except I left out the very begining lines. He held up the bayonet, and said, "This is the M7 Bayonet! Take a good look at it! You will not use it!" and after a few seconds, flipped it to stick in the ground.
Notice that while the Army has really slacked off on bayonet training (compared to WWI, WWII, Korea era), they still have, and issue bayonets. I think the last bayonet charge was in 1944, but the bayonet still gets used every day by GIs, for multitudes of uses, other than stabbing people at rifle's length.
And thats another thing about battle rifles. They are bigger than the carbines. A bit more awkward for mounting and dismounting vheicles, or inside houses, but a bit more mass, and (I think) ruggedness if used as an impact weapon.
Back in the day, we had our doubts about the "mighty mattel" holding up to a fight, and we knew what a wood stocked rifle would take.
Turns out that they held up better than we expected, but its still easier to break plastic and aluminium than steel and heavy wood.
We train, and plan so our guys won't have to go hand to hand with the enemy. But the enemy has plans of his own. Thats why we call them the enemy. A good battle rifle not only delivers "out there", but also delivers when as close as it gets, if you do. The drawback? "Heavy!" (as far as my modest research is concered, troops have been complaining about things being "heavy" since troops first started carrying things. Don't think its going to change soon
), long, awkward....
There's no free lunch in the real world. If you want/need "this" you put up with/pay "that".