I think that as a prepared person, whether you CCW or not, you should carry a good "tactical" light of your preference. I actually prefer the term "personal" light.
Now to be clear, a light on a long gun makes a lot of sense to me. You are better off being able to see the target. It's true a light gives you away, but this cannot be helped. The fact is you can't use a shotgun or a rifle and a light at the same time unless they're integrated.
But on a handgun? For me, nope.
The main issue for me is that I carry my light a lot more places and times than I carry my pistol due to laws. And to be honest I actually have to use a light to assist myself fairly often, much more often than I have to shoot a goblin. Far, far more often.
The fact is I want a "personal" light to be a light, not something I bought primarily because it mounts on a Pitcanny rail. The fact is, if you will let it be, a good personal light is a self defense tool in a myriad of ways. And it's a tool I can take to work with me, it's a tool I can take on an airplane, it's a tool I can take anywhere. Thus when I invest money in a personal light, I want it to be a good light that can function well by itself and
with a handgun.
The other thing is, I'm not an LEO. I have no legal protection from pointing a muzzle at a target. If I see something moving in corner of the parking garage and my good light is on my gun, I'm forced to point a muzzle at an unidentified target to illuminate it. Let's ignore the fact that such is patently unsafe, and that's a pretty big thing to ignore. But can we say lawsuit? Not to mention, imagine you're in a dark parking lot and you see someone with a gun with a light on it pointing it at you. How would you react?
Another thing, and one that tends to be forgotten, is that in the darkness, an armed goblin is going to shoot at the light. If your light is on your gun he's shooting at you. If it's in your extended arm, odds are pretty decent he's shooting air or at least an extremity and not your vitals.
There are ways to coordinate light and gun. It's really not that entirely difficult. It actually comes very naturally. When I practice shooting my carry pistol, I will grab my light in one hand and my gun in the other and practice that way. Try going when it's dark too so you can actually use your light and see what it would be like to really try that. You can also practice readying your light and gun at the same time. It becomes a reflex pretty quick.
A consideration you shouldn't dismiss is that if your gun goes into a courtroom with a light on it... well were you planning on shooting someone that night? Obviously you were or you wouldn't have that evil looking M3 on it.
Finally, and this is just me, a gun is something that I really just want to be a gun if at all possible. I want to look at my gun and say "That is a tool for shooting things. That is its sole purpose." I don't want a light, a laser, an expresso machine, and a video game built into my pistol when it doesn't have to be there. I want no ambiguity in my mind at all as to the purpose of that device. Now in the case of the long gun, the light on the gun is necessary because we need both hands to handle the weapon. I can accept that as a necessary evil you could say.
And I'm not saying there's no use for a light mounted on a handgun. For a cop I think it's a fantastic idea. For the gun that lives in your bedroom it's a good idea, although I personally just sleep with the lights on and get far better illumination that way. I can conceive of how for some people, it would probably work better to have the gun and light all in one package. I can see how that could be an asset to someone if their needs were different than mine.
But for me, I'm avoiding it. I might get an illuminator that mounts on a rail someday, but for right now the Surefire Centurion foots the bill.