I don't abide by the aggressive junk anyway, and though I cuss as a common and frequent part of my vernacular, I don't put that kind of thing on my firearms.
Outside of collectors items, I don't own a firearm which hasn't been modified in some way. More often than not, anything I bring home doesn't go straight into the safe - it goes beside the work bench until it gets cleaned up, properly lubricated, deburred and polished internally.
In my experience, there are three reasons people stand against customization of defensive pistols, none of which I believe make sense, and have never been used to establish premeditation in any legal case, but for which I'm certain this thread is about to draw plenty of "evidence" and an abundance of opinionated support:
1) The presumption factory state is the most reliable state. Only a poor gunsmith leaves a customized pistol in lower function than when he found it. This stance is foolish, in my opinion. Modifications should INCREASE performance of the firearm, without sacrificing functional reliability - if it does anything less, it's NOT an appropriate modification. I've never found, in over 20yrs of paying other smiths work and being paid for it myself off and on for 15yrs, any reason to think a factory condition is the most reliable or most serviceable condition. Since this thread originated in the Zevtech Glock thread, I might point out I have had bone stock, factory delivered Glocks come into my shop which had the same trigger bar issues and trigger block safety issues as described (and berated) in that thread.
2) Customization could be misconstrued as premeditation. Doesn't happen, has never happened in a civilian defensive shooting scenario. The references are about to start pouring from other posters about LEO liability assumptions and ND's where lightened triggers were fired unintentionally. A civilian shouldn't be holding a firearm trained on an assailant, so many offensive LEO paradigms, such as those which drove design changes like the "NYC Triggers," have little to no applicability in civilian defense scenarios.
3) Customization costs money, and if I ever had my defensive pistol confiscated after a shooting, I don't want to have much money invested. It sounds great in theory, but what dollar value do you assign to your life? If the decision were ever forced upon me, I'd be willing to barter a heck of a lot more than $300 to keep a hold on my mortal life.
I CAN - however - fully support the paradigm in which under-knowledged and under-skilled folks should not be performing gunsmithing modifications. If an owner doesn't know how to function test "Bubba's enhanced drop in trigger," he shouldn't be installing it, as he has no way to know whether the installation was successful or not. So the problem isn't with the modification itself, but rather with the "modifier."