Excellent, from Chattanooga. Now we have 'gotten down to brass tacks'.
The very strength, literally, of Kydex is its rigidity. So: if leather were used on such holsters -- for pistols with a bulky or slim light mounted on the rail -- the holster mouth could have, and hopefully would have, been moulded smaller at the lips of it and would have then moved out of the way as the pistol was holstered and drawn.
Kydex simply won't allow this in the thicknesses used in police uniform holsters sold as safety equipment. So the maximum dimension of the light was left for it to enter and exit freely; and this left a sizeable gap.
Safariland then, when noticing the problem at the outset, could have fitted a flexible lip to the rigid Kydex mount, to block entry. I would argue that instead they used the old paradigm -- the trigger was covered like all the pistols before it -- and so that 'counted' as being a complete 'industry standard' build. On the other hand, someone there may have simply looked at the situation and decided 'we HAVE to make this (we can't turn the business away) but it's not our fault (the bed was on fire when I lay down on it).
And so it was with these two views in mind, that I brought up the 'new paradigm since 1985' in the first place. To someone there, it 'looked' like the old problem, but it was a new problem that had simply gone unnoticed since the Glock's introduction; exacerbated by there subsequently having been so many competing pistol designs but no significant holster companies to compete for Kydex holster contracts -- which lack of competition Safariland actually worked hard to create via their technology and related patents (nowadays to the gadgets fitted inside and outside, the leather-lined Kydex 'method' patent having long ago expired).