Respectfully, IMHO this discussion overlooks one critical aspect:
You may be assuming that any use of the rifle for actual self-defense will occur in an environment where you have full use of both arms and hands. In fact, many real life examples indicate you may lose use of either a hand or an entire arm during an encounter. You may need to run that rifle using only one arm and hand.
Will Petty has several videos that explain how to do that with both rifles and handguns, and has conducted training in same with numerous local, state, and federal law enforcement agencies. Note the utility of the ambidexterous charging handle. These videos are worth your review, and perhaps some range time to practice:
AR rifles:
https://www.youtube.com/watch?v=ghy6akCjEnM
Handguns - similar ideas:
https://www.youtube.com/watch?v=zBAcyST32ew
Remember the lessons from the 1986 FBI gunfight with Platt & Matix and Murphy's Law: "whatever can go wrong will, and at the worst possible time". It is true.
It is unwise to expect you will go through an actual engagement retaining full use of all your faculties. Ambidextrous charging handles are worthwhile investments if you ever envision potentially using your rifle in any environment other than a range environment.
Just MHO. YMMV.