If I have the time and opportunity to do what it takes to drop the magazine, I honestly have to believe I'd have considerably more time and opportunity to pull the trigger. It's just easier, quicker and more mechanically natural to do. This whole other concept is simply impossible for me to wrap my mind around.
No, it's not like you're wrong, but more like you've probably not been involved in the sorts of situations in which 'pulling the trigger' was not a practical or even possible alternative.
Fending off an attacker with one hand, while the attacker is trying to wrest the cop's pistol from the holster, and the officer is able to depress the magazine catch before the pistol is removed from the holster ...
Trying to regain control of the unholstered pistol while it's being dominated by an attacker, but not pointed at the attacker, and being inexorably turned toward the officer ...
The attacker's physical domination/struggle has caused the pistol to be slightly out-of-battery, or 'disconnected', and the officer is unable to fire the pistol, but also fears he/she is about to lose control of the pistol ... either from being over-powered or else while being repeatedly struck, kicked, etc., etc. ...
The officer suddenly finds him/herself in a situation where the pistol is NOT going to be fired, but must take an immediate step to deny unauthorized usage of the pistol in case a physical confrontation suddenly presents an enticing access to the holstered pistol by an unauthorized person ... I watched a new cop in FTO trying to detach a rather determined 5150 little old lady from repeatedly attempting to grasp his holstered pistol while he and another cop were trying to contain/restrain her without causing her injury. Popping the magazine and pocketing it denied her easy access to a functioning weapon on the cop's belt while they tried to restrain her without causing causing her injury.
In the same vein, removing the magazine from the holstered pistol while moving a prisoner makes it that much harder for a prisoner to grasp an immediately functioning weapon if things go wrong in an unexpected manner.
Now, we could "what if?" such things endlessly, and someone who dislikes the magazine disconnect concept isn't likely to become convinced it has any practical benefit, or isn't somehow 'dangerous' to the user in some hypothetical situation, but the plain fact is that it has been demonstrated to be practical, useful and even life-saving in a surprising number of LE situations.
Could it also be of similar use in a non-LE situation? Well, as
isp2605 suggested for consideration, why not? Maybe. Possibly.
I know someone who enjoys shooting competitively and who also works for one of the major firearms manufacturers. He doesn't use a pistol equipped with a magazine safety for competition, but the pistol he selected for his wife's nighttime access does have one. He's not concerned about it failing if she ever needs the pistol to fire, but feels it offers her an optional course of action in rendering the weapon temporarily inoperable should she desire. He and she are certainly in the best position to understand their needs, and how to best provide for them.
It's an option ...
... Unless you live in a state which requires new pistols to be equipped with it, of course. Then the 'choice' has been made for you, and you deal with the situation as appropriate.
On the subject of the public having access to LE-involved situations where a magazine safety/disconnect saved an officer's life, as
isp2605 mentioned it's just more than a little unlikely that such information is easily accessible, it at all, to the general public. Some agencies may sometimes track such things internally, and may even share such information with another agency or the firearm's manufacturer, but it simply isn't something commonly put into some file for the purpose of tabulating and 'sharing it' with the public.
Gun magazine authors have shared their first-hand or second-hand knowledge of such things in the past, and probably because they understand how seldom such information works its way out of the LE field into general public knowledge, and that it may be interesting to their readers.
Just because the information isn't considered relevant or necessary for release to the public, that doesn't mean it falls within the category of urban legend, though.
If you don't like the feature, and you're not required to have it in your pistol, what's the need to be all hot & bothered about it or lose any sleep over it's presence in pistols belonging or being used by someone else? I don't make any money of them, and couldn't care less what other folks thought about them outside of my immediate interest and control.
Are the same folks who have such volatile reactions to the presence of a magazine safety/disconnect on a pistol also horrified by the presence of a 'kill-switch' on modern motorcycles?
What if the button is hit while zooming down the freeway?
What if it malfunctions and kills the motor when the rider desperately needs it?
On the other hand, the way things seem to be moving toward 'safety considerations' when it comes to firearms, I won't be at all surprised if increasingly more states consider it a mandatory feature on new pistols imported into their states as time passes.
I like the way that S&W has made the magazine safety & ILS optional features in their MP pistol line, except for those states which have already enacted legislation requiring such things, of course. I wish they did the same thing when it comes to the ILS in their revolvers ...