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.
Next what do you call significant? When we speak of such things it is usually relative to the situation and device in question. A failed transmission in a car is a warranty headache, a failed helicopter transmission has a body count much of the time. Given that many people use a gun for self defense this would make most want to minimize the chance of mechanical failure.
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.
If you do not consider the number significant, I certainly am not going to try and convince you otherwise however I would hope that you can see the other side of the argument for those who do consider the lock to be an issue.
In addition please realize that many of us have had to turn many fasteners we do not have a bit or fitting for or defeat locks for which the key is lost or gone. Spend enough time doing this and you look at anything pretending to be a lock a lot differently from say a decent pad lock, door lock, safe etc. The ILS is definitely a pretend lock much the same way luggage and brief case locks are pretend locks, yes the will slow someone down but not by much and the false sense of security especially when it comes to a gun may be a very bad side effect.