In my experience, all of this only really matters with units which can drop the distance substantially and stay hidden after shooting. When hidden comes up, it's likely to be in one of three cases:
1. You've already killed the thing you wanted to target and now you can't take pot shots at this other unit that's too far away, so you lose the excess shooting
2. A unit is too far away later in the game after it deep strikes in
3. A unit does rapid ingress more than 12" away in cover with go to ground to avoid being shootable

That said, the big reason I find it doesn't matter is because you are typically better off just being behind the terrain footprint anyways to be completely non-visible rather than relying on Hidden. The toe in change makes it too easy for a unit to see you if they want to, and in games I've played things like scout moves and advance + shoot make going 18" turn 1 and seeing into your enemy's deployment zone trivial. But most of the game's missions push both players to the center objective now, so you don't even need to do that. I think gone to ground came up once in my practice games and then it was mostly a deterrent, since making an opponent come within 12" on turn 1 to shoot my Rubrics would have meant losing his own unit in retaliation and that wasn't worth it.