Fascinating topic. I am mostly an LPVO carbine guy, but do a little bit of the long-range thing with my bolt guns when I can spare time for a run to PNTC. The answer is, yes, I use it, especially on 1x.
The necessity of illumination sometimes depends on reticle design. You see this a lot with "floating" FFP reticle paradigms like horseshoes where having a bright red point in the middle of your scope is a huge help in quickly locating the reticle on 1x. The Razor Gen3 gets away with doing this (albeit it's not exactly a horseshoe) because it has nuclear bright illumination capability; the competition largely doesn't, which makes them less great to use on 50yd target arrays in multi-gun.
But if were talking something like an SFP LPVO with a duplex-based reticle, you can design reticles that are not so illumination dependent. C-More's TJ1I reticle, for example, is one of my favorites because it combines the duplex reticle with a 1.5 MOA dot in the middle. It illuminates pretty well, but if it starts getting overpowered by ambient light on a glinting target, you still have a very well-defined aiming point to use. Vortex's JM-1 reticle, on the other hand, skips the larger dot because it can fall back on its super bright FO-illuminated .5 MOA dot (Sig uses a similar paradigm for their Hellfire reticles). It's still very usable without illumination, but I don't think it's as good in certain circumstances.
But beyond a hundred yards, unless ambient light is inadequate or the target is dark / on a dark background and I need assistance finding my reticle, there's not a lot of need for illumination in my usage. A scope like the XTR III lacking illumination wouldn't make much of a difference in my decision to buy it, especially since I don't hunt. YMMV, etc.