HoraceHogsnort...
The world is generally neither a fair nor rational place. As noted, some prosecutors are not friendly toward self-defense use of guns in the first place, and may look for vulnerable angles.
Also as noted, lawyers may have better odds of getting a civil win for negligent homicide/manslaughter than they would for a valid, justifiable, SD homicide.
So.... it has been attempted, and at least in one case (according to the Ayoob article) it seems to have been attempted, successfully.
And once again, legal issues aside - the advantage to a DA system is that it makes accidental pulls of the trigger less likely, when under stress. From a practical standpoint, at typical SD ranges, there is no real advantage to cocking a DA hammer, and there are definite disadvantages (legal exposure; possibility of an actual AD/ND; even the split second of time required to cock the hammer).
If you want to use a DA system, learn how to shoot DA. You might be surprised at the results that can be achieved.
Examples: I just picked up this Smith and Wesson 442 for the first time, yesterday. Added CTC J-frame grips. Test fired it using standard pressure, flash-suppressed Buffalo Bore 158gr LSWCHP at an advertised 850fps.
At five yards, bottom group shot using laser, middle and upper groups shot using fixed sights:
Of course, those were fired fairly slowly, to check point of aim. (I'll adjust the laser next time out; gun hits about 4" above the dot at 5yds, and I'd prefer it to be about 1.5" high and .5" left, to minimize parallax over distance.) For defensive purposes, this big group consists of 15 rounds of the 158gr LSWCHP loads, fired as fast as I could bring sights back on target, again at 5 yds:
Note: reduced scale silhouettes; for perspective, on the aimed fire targets, both the bottom and middle groups would fit inside the trigger guard of the 442.
Note2: I mostly shoot SA autos; DA revolvers are secondary for me. Imagine what you could do if you really practiced....