You state: "The fact of the matter is that safety and reliability has not been significantly compromised by the addition of the ILS" and "I've seen no evidence that their rate of breakage/malfunction is enough higher since the introduction of the ILS to be statistically significant".
So let’s start with statistics, what are you sources for what guns pre-and post lock. You are presenting arguments as if you have hard, data on this matter and if you do I personally would be interested in seeing it. If you don't have some hard numbers it's fine, lets just not act as if we do have that data.
Well, there have only been two documented and verifiable incidents of the ILS "auto locking" that I'm aware of, one reported by Michael Bane and the other reported by Massad Ayoob. That is not to say that it hasn't happened more, but all the other reports I've seen are anonymous posts on internet fora which, as I mentioned before, are unreliable. There are several reasons that internet posts are unreliable. Most obviously, the honesty of the poster is unverifiable and thus a reported "auto lock" could be nothing more than someone with an axe to grind or simply someone who likes to stir the pot. Secondly, the poster's expertise in diagnosing the problem is often unknown so a revolver that actually locked up for some other reason might have its issues mistakenly blamed on the ILS. Finally, a poster may post his experience on multiple fora under multiple handles thus making one incident appear to be many. Likewise, if more than one person was present when the incident occurred, you may have multiple people posting about what is, in fact, one incident and thereby also making one incident seem like many.
Now, from 2001 (the year that the lock was introduced) until 2010 (2011 and 2012 figures aren't available yet) S&W has produced 1,554,248 revolvers according to the ATF's statistics. If we only take the two documented cases, that's a failure rate of approximately 0.000129%. Even if we're extremely generous and assume a failure rate of 100 per year (which I very highly doubt), that gives us a total failure rate of only 0.0643%. If we take it even a step further and assume the ridiculously high failure rate of 1,000 per year, we're still only at 0.643%. In order to get a 1% failure rate, we would have to have an average of just over 1,554 "auto locks" per year.
So, even if we have a failure rate of 0.643%, that would still be a grand total of 10,000 "auto locks" over a ten year period and I'd think that we'd have more than two documented, verifiable incidents particularly since so many people want so badly to prove that the lock is the horrible, awful thing that they claim it is. Of course, if you know of documented cases that I don't, please share them.
I will grant you that the smith ILS has a "low" chance of failing. Is it 0.1%, 0.01% or .00001%? I do not know, and neither I suspect do you. However the fact is however low the chance is the lock can not fail if it is not there. FURTHERMORE in medicine, aerospace and other fields we routinely invest massive sums of money in engineering, equipment and materials to reduce or eliminate failure modes that are as small a percentage as the ILS number is likely to be. Therefore I personally do not think it is unreasonable that some people, myself included consider this significant and seek to eliminate the ILS from our guns either by not purchasing or disabling it.
I can't speak for aircraft, but medical equipment often has a much higher failure rate than you're giving it credit for. For example, my father works in a 200-bed hospital which has a 10% ventilator-to-bed ratio. I asked him if 1 ventilator per year failing (which would be a 5% failure rate) is excessive and he informed me that actually, in his experience, the failure rate is typically much higher. It is for this reason that ventilators have multiple alarms and per policy are checked at least every two hours and that the vital components of the ventilators are proactively replaced after a predetermined number of hours in use. Also, I have a very difficult time believing that a piece of medical equipment like a ventilator or an aircraft can be held to a higher standard of reliability than a revolver regardless of the money spent because a ventilator or airplane is an exponentially more complicated machine than any revolver ever produced.
If we are to hold firearms to the same standards that medical equipment is, then we should be inspecting them at least daily, if not multiple times per day and having a gunsmith replacing all the vital parts after a predetermined number of rounds whether they're causing problems or not. Fortunately, firearms generally do not require as intensive maintenance as medical equipment does because they are not nearly as complex.