The rule of 3's is as operative today as it ever was, but just because we know most encounters happen up close does not mean we should forget developing skills for shooting at distance. The reason we spend so much time training for bad breath distance encounters is not only that they are the most likely, but also because they happen so damn fast. Training for close encounters incorporates factors other than just shooting. Like other defensive maneuvers, the draw, and moving, and going to cover, and getting inside your opponent's decision loop, and follow through, and dealing with tunnel vision and auditory exclusion.
But distance is your friend in a lethal encounter. It gives you more options. Get as much distance and cover between and your opponent as possible.
I spend 80% of my time training for up close and personal encounters. Then I move back, to the 25, and 50, and then on to the 100. I know I can hit an IDPA silhouette 8 out of 10 times from 100 yards with iron sights on my carry pistol, but only because I and a few friends have sent a LOT of rounds down range practicing it. This is why, by the way, I carry a full sized pistol as my daily carry rather than one of my micro pistols-I am more precise with it. However, a late friend who was a DEA instructor could hit an 8" plate consistently with a Sig P238 .380 at 100. It's all about building skills. I don't advocate everyone training at 100 yards with their pistol, but it is good to know the capabilities are there and to have the option if you need it. The point being, if you don't practice at distance with the gun you carry, optics or not, you probably are not going to hit the target if you find yourself in that situation.
As far as optics on your carry pistol, do what you have to do to win. Cheat if it works. As Bill Jordan said, there is no second place winner.