Personally, I think some are placing too much confidence in their ability to see every possible threat because they are so "situationally aware". Even the best are sometimes distracted and find themselves in an undesirable spot.

There is a gentleman in california who owns a company that trains security people (executive protection types - not Walmart Security) & trains martial arts TEACHERS in tactics. Needless to say, he holds black belts in 5 or 6 arts and is a firearms instructor.
One day, while at an ATM, he found himself facing three thugs (one armed with a baton) who wanted to rob him. By the time the police arrived all three were on the deck, writhing in pain with no "visible" injuries. It took the police a few second to realize that HE was the victim.
The point being that if your plan is to use your "situational awareness" to avoid all threats - you need a new plan!
I'm not saying you have to become like my friend, but everyone should know a technique or two for close quarter encounters. You may need it in order to even get to your gun.