I apologize if this is a repeat but I felt that this needed to defiantly be mentioned... first of I think the scope zeroing would highly improve long range shooting as well as giving the range finder a purpose besides stat boosting.
1. Make it so can zero in your scope (100mm, 200, 300, 400, 500+)
2. Implement a function to the range finder such as point and it tells you the range of the crosshair.
3. Have a much happier community with an easy fix.
They made it this way so you would be forced to engage the enemy, otherwise, outside their radius of vision, you can take pot shots at them and they won't even know it. Plenty of videos showing the enemy ai being killed by semi long shots and they don't react at all. Plenty of videos showing that if they happen to spot the shot, now they will come get you where ever you try to hide.
I fail to see why it would make any difference regardless since people will snipe regardless, this simply just makes it more realistic and fun... and yes what you say has some very valid points but like everything else I'm sure they can find a way to balance it (such as a helicopter to fly by once they are alerted) =)