Are ambidextrous controls important to your firearms preps?

I for the life of me can't understand why there aren't more ambidextrous firearms out of the box. I never understood why the military too, after all this time still doesn't put ambi controls as a standard on issue weapons like the M4 and M16 when there are so many lefthanded users and a person can need to switch to weakhand shooting for better cover or being hurt. I finally got around to changing out my charging handle on my AR-15 to an ambi charging handle after deciding it was just better off in speed of manipulation, having it instead of always working around the standard charging handle as a lefty, because it was standard. Now the rifle is set up with that and the shortened modified ambi safety. The magazine release and bcg release are useable for both, but I may change them out. I've had lots of AR's and always left them, but is it the best choice. I went to the range with a buddy the other day and taught him to run the AR having never fired one before. He loved it of course and wants one bad now. He doesn't have much firearms experience though, but they are a good rifle and he ran it well for the first time. The added ambi controls makes it very useable for both users whether righty or lefty and I think that's important in shtf firearm preps seeing how you may need have someone run a weapon you have and they may be a lefty or a righty. How do you feel about it?