Some people don't view it as a safety feature. I carried a DA Beretta 96FS on police patrol and I carried with the manual safety engaged to extend the time a potential gungrabber needed to figure out how to get the gun running.
I will say that such a feature could come in handy. I knew of a K9 officer who had his weapon taken from him and the perp pulled the trigger several times trying to kill the officer but the safety was engaged. The officer pulled out his backup pistol and killed the scumbag. However, the officer was using a level I holster and foolishly wrestled with the perp with poor weapon retention techniques. His backup pistol was also not secured very well. The officer also decided to do a "tombstone" and go after a group of 4 gangbangers by himself. Very poor judgement all around.
A good triple retention holster would be a better option in my opinion. Quite a few perps know their guns and will likely figure out how to get the pistol running versus figuring out how to get the pistol out of a good level III holster. You're practically never going to find non-cops that know how to use a good level III holster and will fumble much more with that than more well known safety features on a pistol.