Why a weapon mounted light?

As I mentioned in my recent YouTube review, my preference is for each home defense firearm have a weapon mounted light.  In the absence of that, I insist on a good, reliable, BRIGHT yet compact flashlight be stored with a home defense firearm.  The reasons for this are self evident, we really shouldn't be using a firearm to engage an unknown target and MOST home invasions tend to occur in evening or nighttime hours.  But, WHY should the light be mounted on the weapon, instead of being handheld?

Firstly, the reasons to employ an independent, handheld light are numerous.  You have the ability to use the light WITHOUT drawing or muzzling your target.  That adds an element of safety and utility to the light, and would be my preference for a conceal carry firearm. Many firearms were built without any provision for a rail.  It adds weight to the muzzle end of the firearm.  Yes, correct on all counts.

But, mounting a weapon light also insures that every time that gun hits  your hand you have the ability to both illuminate and disorientate your potential opponent.  I'm not sure if any reader has had the displeasure of having 600 lumens rammed into your retinas, but the above picture gives you an idea of how little you can really see when a weapon light shines into your eyeballs.  Nothing, absolutely nothing, on top of an instant reflex to squint, and a wicked pain and big white blog in the center of your vision for a couple minutes (practice room clearing and shine your light into a mirror, no it isn't pleasant.)

Also note that I have the ability to free a hand while keeping a target illuminated and held at gunpoint.  Think about drawing down on a home intruder, he surrenders, you need to call the cops.  If you have gun in one hand and light in the other, exactly which one do you WANT TO PUT DOWN to call the police?  In my case, I have a small child, and the likelihood is I will have to pick her up and forcibly move her in the middle of the night.  Having the light on my gun, at my fingertips, let's me have a free hand to get my family to the fall back room in our home.

There are perfectly justifiable and defensible reasons to eschew a weapon mounted light.  There are perfectly justifiable reasons to mount one.  Consider your options, your pros and cons, your situation, and let us know what you think?