But you have to realize that you don't have to deal with those folks. Dedication and willingness to work aren't the characteristics of the jackal. Criminals are primarily opportunistic predators who aren't looking for any fight. It puts them at risk of being able to continue their life-style and of maintaining their status in the pack.
It is a mistake to compare dedicated martial artists to punks and criminals who are opportunistic bullies.
You won't face dedicated marital artists when dealing with most criminals.
It is also a mistake for MA practitioners who spend their life in the gym/dojo to assume that they understand how to deal with an ambush style attack or how the'll react. The "rules" are different.
What is important is to practice to the point that your action comes without conscious thought so that you can focus on what instead of how to do while developing the mindset to fight without limitation when forced to. An attack on the street is NOT a 3 minute open sparring session in the dojo. It is a threat to your life without rules or tapout or referees.
Any student of MA should spend some time training with Southnarc and other street defense experts to help them understand the difference so that they can survive. I've made it through 3 violent attacks without being put in the hospital and it is a world of difference from full contact rules fights, but I'm also certain the training, both for mindset and skills, that I had at the time made the difference.
The original question was whether a gun is "enough". The answer resoundingly is that statistics show us that YES is the answer millions of times a year. BUT the facts are that many street attacks occur as ambushes and that there are those instances where time to draw isn't granted to you so you have to use other skills to make the distance to draw or to defend yourself without drawing. There is no one ideal solution to the whole spectrum of self defense problem. Personal experience has taught met that.
BTW, 3 minute sets are not "first touch" whether light or full contact.
Lots of very good points in here, I see what you mean about not facing a trained opponent. But I am considering the thug who is well versed in street fighting. I have faced some "experienced" guys while working as a bouncer and it was frightening what they had picked up from fights and watching the UFC, certainly a wake up call.