Gun lights have always had the same arguments, back and forth.
I used to say I would never have one on my guns. Now I do, because the new lights are so bright, that once you hit someone with a direct beam or strobe, they are blinded. I have tried it on myself in daylight and could not see anything but spots for almost 5 minutes.
If you just turn it on and point the light at the floor or ceiling, you will light up the entire room, as a few have already mentioned, no need to point the muzzle at the bad guy, until you are sure he is a bad guy.
But he will be blinded and you should be moving anyhow.
So even if he fires in the general direction of the flashing light, you are no longer there. By then you should have decided if it's a go or no go situation, and it whould be over.
Outside the house in complete darkness is another story, if you are going to light someone up, it's going to be trickier, because you really can't see what's behind the person to a satifactory degree, and depending on the light you are using. But it's better to have the option and never have to use it.
I still have several Tac lights along with my Glock with the TLR4 on it.