While I appreciate the gun-biased bravado, the point here is that use of firearms is not always possible and not always prudent. More over, in cases of close proximity, it is often quicker to respond with means of force OTHER than the drawing and firing of a gun. This was the case, for example with the shootings of Reagan and of Oswald. By the time agents and officers had guns drawn, the shooters were already downed...and those were professionals drawing their guns.
Think about it. For most people in a crisis, the first and often longest delay in responding correctly is the delay that comes from the lack of recognition of what is going on, often spawned by a sense of disbelief that something could be going wrong or misconception about the nature of what is going on. That can last from a fraction of a second to several seconds.
Once proper recognition is made, then a decision to react occurs and this takes time. If the decision to draw and fire a gun is the decision made, then it will be for most folks who are not aware that they are going to be in a situation where they are about the draw and fire, 2-4 seconds time before they will get shots on target. Bear in mind that you general CCW person isn't a Quckdraw McGraw who practices drawing and firing at the range every week. Most haven't even been to the range this year, much less worked on their draw skills.
So as noted in the Northwood, MO church example I posted yesterday, if you are standing there in a service and a guy walks into the service and is standing next to you and starts shooting, do you really think the most timely action is going to be to draw and fire your own gun? You can do that in 2-4 seconds from the time you decide your course of action or you can be tackling him in less than 1. Which do you see as the one most apt to stop the shooter sooner from carrying out his intended goal?
Now if the shooter is across the room, street, etc., then sure enough, tackling may not be the best of options if you are indeed armed, but a lot of the shooters that are tackled are tackled early on and when they are in close proximity to the responding people, not all, but many based on reading over the examples here.